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draft-ietf-calsch-ical-07.txt:

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     The property parameter CN, is for the common or displayable name
     associated with the calendar address; ROLE, for the intended role that
     the attendee will have in the calendar component; PARTSTAT, for the
     status of the attendee's participation; RSVP, for indicating whether the
     favor of a reply is requested; CUTYPE, to indicate the type of calendar
     user; MEMBER, to indicate the groups that the attendee belongs to;
     DELEGATED-TO, to indicate the calendar users that the original request
     was delegated to; and DELEGATED-FROM, to indicate whom the request was
     delegated from; SENT-BY, to indicate whom is acting on behalf of the
     ATTENDEE; and DIR, to indicate the URI that points to the directory
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     be specified on an "ATTENDEE" property in either a "VEVENT", "VTODO" or
     "VJOURNAL" calendar component. They MUST not be specified in an
     "ATTENDEE" property in a "VFREEBUSY" or "VALARM" calendar component. If
     the LANGUAGE property parameter is specified, the identified language
     applies to the CN parameter.

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--------------------------------------------------------------------------------


2	Network Working Group                               Frank Dawson, Lotus
3	Internet Draft                               Derik Stenerson, Microsoft
4	<draft-ietf-calsch-ical-07.txt
5	Expires six months after                                   May 11, 1998

7	     Internet Calendaring and Scheduling Core Object Specification
8	                              (iCalendar)

10	Status of this Memo

12	   This memo is an Internet-Draft. Internet-Drafts are working documents
13	   of the Internet Engineering Task Force (IETF), its areas, and its
14	   working groups. Note that other groups can also distribute working
15	   documents as Internet-Drafts.

17	   Internet-Drafts are draft documents valid for a maximum of six
18	   months. Internet-Drafts can be updated, replaced, or made obsolete by
19	   other documents at any time. It is not appropriate to use Internet-
20	   Drafts as reference material or to cite them other than as a "working
21	   draft" or "work in progress".

23	   To view the entire list of current Internet-Drafts, please check
24	   the "1id-abstracts.txt" listing contained in the Internet-Drafts
25	   Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net
26	   (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au
27	   (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu
28	   (US West Coast).

30	   Distribution of this memo is unlimited.

32	   Copyright (C) The Internet Society 1997. All Rights Reserved.

34	Abstract

36	   There is a clear need to provide and deploy interoperable calendaring
37	   and scheduling services for the Internet. Current group scheduling
38	   and Personal Information Management (PIM) products are being extended
39	   for use across the Internet, today, in proprietary ways. This memo
40	   has been defined to provide the definition of a common format for
41	   openly exchanging calendaring and scheduling information across the
42	   Internet.

44	   This memo is formatted as a registration for a MIME media type per
45	   [RFC 2048]. However, the format in this memo is equally applicable
46	   for use outside of a MIME message content type.

48	   The proposed media type value is 'text/calendar'. This string would
49	   label a media type containing calendaring and scheduling information
50	   encoded as text characters formatted in a manner outlined below.

52	   This MIME media type provides a standard content type for capturing
53	   calendar event, to-do and journal entry information. It also can be
54	   used to convey free/busy time information. The content type is
55	   suitable as a MIME message entity that can be transferred over MIME
56	   based email systems, using HTTP or some other Internet transport. In
57	   addition, the content type is useful as an object for interactions
58	   between desktop applications using the operating system clipboard,
59	   drag/drop or file systems capabilities.

61	   This memo is based on the earlier work of the vCalendar specification
62	   for the exchange of personal calendaring and scheduling information.
63	   In order to avoid confusion with this referenced work, this memo is
64	   to be known as the iCalendar specification.

66	   Readers may also refer to the calendaring and scheduling model
67	   defined in [ICMS] for a description of this Internet application.

69	   This memo defines the format for specifying iCalendar object methods.
70	   An iCalendar object method is a set of usage constraints for the
71	   iCalendar object. For example, these methods might define scheduling
72	   messages that request an event be scheduled, reply to an event
73	   request, send a cancellation notice for an event, modify or replace
74	   the definition of an event, provide a counter proposal for an
75	   original event request, delegate an event request to another
76	   individual, request free or busy time, reply to a free or busy time
77	   request, or provide similar scheduling messages for a to-do or
78	   journal entry calendar component. The iCalendar Transport-indendent
79	   Interoperability Protocol (iTIP) defined in [ITIP] is one such
80	   scheduling protocol.

82	   Table of Contents

84	1 Introduction.........................................................6
85	2 Basic Grammar and Conventions........................................6
86	 2.1 Formatting Conventions ...........................................7
87	 2.2 Related Memos ....................................................8
88	 2.3 International Considerations .....................................8
89	3 Registration Information.............................................8
90	 3.1 Content Type .....................................................9
91	 3.2 Parameters .......................................................9
92	 3.3 Content Header Fields ...........................................10
93	 3.4 Encoding Considerations .........................................10
94	 3.5 Security Considerations .........................................10
95	 3.6 Interoperability Considerations .................................11
96	 3.7 Applications Which Use This Media Type ..........................11
97	 3.8 Additional Information ..........................................11
98	 3.9 Magic Numbers ...................................................11
99	 3.10 File Extensions ................................................11
100	 3.11 Contact for Further Information: ...............................12
101	 3.12 Intended Usage .................................................12
102	 3.13 Authors/Change Controllers .....................................12
103	4 iCalendar Object Specification......................................12
104	 4.1 Content Lines ...................................................12
105	  4.1.1 List and Field Separators ....................................15
106	  4.1.2 Multiple Values ..............................................15
107	  4.1.3 Binary Content ...............................................16
108	  4.1.4 Character Set ................................................16
109	 4.2 Property Parameters .............................................16
110	  4.2.1 Alternate Text Representation ................................17
111	  4.2.2 Common Name ..................................................18
112	  4.2.3 Calendar User Type ...........................................19
113	  4.2.4 Delegators ...................................................19
114	  4.2.5 Delegatees ...................................................20
115	  4.2.6 Directory Entry Reference ....................................20
116	  4.2.7 Inline Encoding ..............................................20
117	  4.2.8 Free/Busy Time Type ..........................................21
118	  4.2.9 Language .....................................................22
119	  4.2.10 Group or List Membership ....................................22
120	  4.2.11 Participation Status ........................................23
121	  4.2.12 Recurrence Identifier Range .................................24
122	  4.2.13 Alarm Trigger Relationship ..................................25
123	  4.2.14 Relationship Type ...........................................25
124	  4.2.15 Participation Role ..........................................26
125	  4.2.16 RSVP Expectation ............................................27
126	  4.2.17 Sent By .....................................................27
127	  4.2.18 Time Zone Identifier ........................................27
128	  4.2.19 Value Data Types ............................................28
129	 4.3 Property Value Data Types .......................................29
130	  4.3.1 Binary .......................................................29
131	  4.3.2 Boolean ......................................................30
132	  4.3.3 Calendar User Address ........................................30
133	  4.3.4 Date .........................................................31
134	  4.3.5 Date-Time ....................................................31
135	  4.3.6 Duration .....................................................33
136	  4.3.7 Float ........................................................34
137	  4.3.8 Integer ......................................................34
138	  4.3.9 Period of Time ...............................................35
139	  4.3.10 Recurrence Rule .............................................36
140	  4.3.11 Text ........................................................40
141	  4.3.12 Time ........................................................41
142	  4.3.13 URI .........................................................43
143	  4.3.14 UTC Offset ..................................................44
144	 4.4 iCalendar Object ................................................45
145	 4.5 Property ........................................................45
146	 4.6 Calendar Components .............................................45
147	  4.6.1 Event Component ..............................................46
148	  4.6.2 To-do Component ..............................................48
149	  4.6.3 Journal Component ............................................49
150	  4.6.4 Free/Busy Component ..........................................50
151	  4.6.5 Time Zone Component ..........................................52
152	  4.6.6 Alarm Component ..............................................58
153	 4.7 Calendar Properties .............................................61
154	  4.7.1 Calendar Scale ...............................................61
155	  4.7.2 Method .......................................................62
156	  4.7.3 Product Identifier ...........................................63
157	  4.7.4 Version ......................................................63
158	 4.8 Component Properties ............................................64
159	  4.8.1 Descriptive Component Properties .............................64
160	    4.8.1.1 Attachment ...............................................64
161	    4.8.1.2 Categories ...............................................65
162	    4.8.1.3 Classification ...........................................66
163	    4.8.1.4 Comment ..................................................67
164	    4.8.1.5 Description ..............................................67
165	    4.8.1.6 Geographic Position ......................................68
166	    4.8.1.7 Location .................................................69
167	    4.8.1.8 Percent Complete .........................................69
168	    4.8.1.9 Priority .................................................70
169	    4.8.1.10 Resources ...............................................72
170	    4.8.1.11 Status ..................................................72
171	    4.8.1.12 Summary .................................................73
172	  4.8.2 Date and Time Component Properties ...........................74
173	    4.8.2.1 Date/Time Completed ......................................74
174	    4.8.2.2 Date/Time End ............................................75
175	    4.8.2.3 Date/Time Due ............................................75
176	    4.8.2.4 Date/Time Start ..........................................76
177	    4.8.2.5 Duration .................................................77
178	    4.8.2.6 Free/Busy Time ...........................................78
179	    4.8.2.7 Time Transparency ........................................79
180	  4.8.3 Time Zone Component Properties ...............................79
181	    4.8.3.1 Time Zone Identifier .....................................79
182	    4.8.3.2 Time Zone Name ...........................................80
183	    4.8.3.3 Time Zone Offset From ....................................81
184	    4.8.3.4 Time Zone Offset To ......................................82
185	    4.8.3.5 Time Zone URL ............................................82
186	  4.8.4 Relationship Component Properties ............................83
187	    4.8.4.1 Attendee .................................................83
188	    4.8.4.2 Contact ..................................................85
189	    4.8.4.3 Organizer ................................................86
190	    4.8.4.4 Recurrence ID ............................................87
191	    4.8.4.5 Related To ...............................................88
192	    4.8.4.6 Uniform Resource Locator .................................89
193	    4.8.4.7 Unique Identifier ........................................90
194	  4.8.5 Recurrence Component Properties ..............................91
195	    4.8.5.1 Exception Date/Times .....................................91
196	    4.8.5.2 Exception Rule ...........................................92
197	    4.8.5.3 Recurrence Date/Times ....................................93
198	    4.8.5.4 Recurrence Rule ..........................................95
199	  4.8.6 Alarm Component Properties ..................................102
200	    4.8.6.1 Action ..................................................103
201	    4.8.6.2 Repeat Count ............................................103
202	    4.8.6.3 Trigger .................................................104
203	  4.8.7 Change Management Component Properties ......................105
204	    4.8.7.1 Date/Time Created .......................................105
205	    4.8.7.2 Date/Time Stamp .........................................106
206	    4.8.7.3 Last Modified ...........................................107
207	    4.8.7.4 Sequence Number .........................................107
208	  4.8.8 Miscellaneous Component Properties ..........................109
209	    4.8.8.1 Non-standard Properties .................................109
210	    4.8.8.2 Request Status ..........................................110
211	5 iCalendar Object Examples..........................................111
212	6 Recommended Practices..............................................115
213	7 Registration of Content Type Elements..............................116
214	 7.1 Registration of New and Modified iCalendar Object Methods ......116
215	 7.2 Registration of New Properties .................................116
216	  7.2.1 Define the property .........................................116
217	  7.2.2 Post the Property definition ................................117
218	  7.2.3 Allow a comment period ......................................117
219	  7.2.4 Submit the property for approval ............................117
220	 7.3 Property Change Control ........................................118
221	8 References.........................................................118
222	9 Acknowledgments....................................................120
223	10 Author's Address..................................................120
224	11 Full Copyright Statement..........................................121
225	1  Introduction

227	   The use of calendaring and scheduling has grown considerably in the
228	   last decade. Enterprise and inter-enterprise business has become
229	   dependent on rapid scheduling of events and actions using this
230	   information technology. However, the longer term growth of
231	   calendaring and scheduling, is currently limited by the lack of
232	   Internet standards for the message content types that are central to
233	   these knowledgeware applications. This memo is intended to progress
234	   the level of interoperability possible between dissimilar calendaring
235	   and scheduling applications. This memo defines a MIME content type
236	   for exchanging electronic calendaring and scheduling information. The
237	   Internet Calendaring and Scheduling Core Object Specification, or
238	   iCalendar, allows for the capture and exchange of information
239	   normally stored within a calendaring and scheduling application; such
240	   as a Personal Information Manager (PIM) or a Group Scheduling
241	   product.

243	   The calendaring and scheduling model, defined in the [ICMS], is a
244	   useful reference to terms and the general framework of this Internet
245	   application.

247	   The iCalendar format is suitable as an exchange format between
248	   applications or systems. The format is defined in terms of a MIME
249	   content type. This will enable the object to be exchanged using
250	   several transports, including but not limited to SMTP, HTTP, a file
251	   system, desktop interactive protocols such as the use of a memory-
252	   based clipboard or drag/drop interactions, point-to-point
253	   asynchronous communication, wired-network transport, or some form of
254	   unwired transport such as infrared might also be used.

256	   The memo also provides for the definition of iCalendar object methods
257	   that will map this content type to a set of messages for supporting
258	   calendaring and scheduling operations such as requesting, replying
259	   to, modifying, and canceling meetings or appointments, to-dos and
260	   journal entries. The iCalendar object methods can be used to define
261	   other calendaring and scheduling operations such a requesting for and
262	   replying with free/busy time data. Such a scheduling protocol is
263	   defined in the iCalendar Transport-independent Interoperability
264	   Protocol (iTIP) defined in [ITIP].

266	   The memo also includes a formal grammar for the content type based on
267	   the Internet ABNF defined in [RFC 2234]. This ABNF is required for
268	   the implementation of parsers and to serve as the definitive
269	   reference when ambiguities or questions arise in interpreting the
270	   descriptive prose definition of the memo.

272	2  Basic Grammar and Conventions

274	   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
275	   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" and
276	   "OPTIONAL" in this document are to be interoperated as described in
277	   [RFC 2119].

279	   This memo makes use of both a descriptive prose and a more formal
280	   notation for defining the calendaring and scheduling format.

282	   The notation used in this memo is the ABNF notation of [RFC 2234].
283	   Readers intending on implementing this format defined in this memo
284	   should be familiar with this notation in order to properly interpret
285	   the specifications of this memo.

287	   All numeric and hexadecimal values used in this memo are given in
288	   decimal notation.

290	   All names of properties, property parameters, enumerated property
291	   values and property parameter values are case-insensitive. However,
292	   all other property values are case-sensitive, unless otherwise
293	   stated.

295	        Note: All indented editorial notes, such as this one, are
296	        intended to provide the reader with additional information. The
297	        information is not essential to the building of an
298	        implementation conformant with this memo. The information is
299	        provided to highlight a particular feature or characteristic of
300	        the memo.

302	   The format for the iCalendar object is based on the syntax of the
303	   [MIME DIR] content type. While the iCalendar object is not a profile
304	   of the [MIME DIR] content type, it does reuse a number of the
305	   elements from the [MIME DIR] specification.

307	2.1 Formatting Conventions

309	   The mechanisms defined in this memo are defined in prose. Many of the
310	   terms used to describe these have common usage that is different than
311	   the standards usage of this memo. In order to reference within this
312	   memo elements of the calendaring and scheduling model [ICMS], core
313	   object (this memo) or interoperability protocol [ITIP] some
314	   formatting conventions have been used. Calendaring and scheduling
315	   roles defined by [ICMS] are referred to in quoted-strings of text
316	   with the first character of each word in upper case. For example,
317	   "Organizer" refers to a role of a "Calendar User" within the
318	   scheduling protocol defined by [ITIP]. Calendar components defined by
319	   this memo are referred to with capitalized, quoted-strings of text.
320	   All calendar components start with the letter "V". For example,
321	   "VEVENT" refers to the event calendar component, "VTODO" refers to
322	   the to-do calendar component and "VJOURNAL" refers to the daily
323	   journal calendar component. Scheduling methods defined by [ITIP] are
324	   referred to with capitalized, quoted-strings of text. For example,
325	   "REQUEST" refers to the method for requesting a scheduling calendar
326	   component be created or modified, "REPLY" refers to the method a
327	   recipient of a request uses to update their status with the
328	   "Organizer" of the calendar component.

330	   The properties defined by this memo are referred to with capitalized,
331	   quoted-strings of text, followed by the word "property". For example,
332	   "ATTENDEE" property refers to the iCalendar property used to convey
333	   the calendar address of a calendar user. Property parameters defined
334	   by this memo are referred to with lowercase, quoted-strings of text,
335	   followed by the word "parameter". For example, "value" parameter
336	   refers to the iCalendar property parameter used to override the
337	   default data type for a property value. Enumerated values defined by
338	   this memo are referred to with capitalized text, either alone or
339	   followed by the word "value". For example, the "MINUTELY" value can
340	   be used with the "FREQ" component of the "RECUR" data type to specify
341	   repeating components based on an interval of one minute or more.

343	2.2 Related Memos

345	   Implementers will need to be familiar with several other memos that,
346	   along with this memo, form a framework for Internet calendaring and
347	   scheduling standards. This memo, [ICAL], specifies a core
348	   specification of objects, data types, properties and property
349	   parameters.

351	   [ICMS] - specifies a common terminology and abstract model;

353	   [ITIP] - specifies an interoperability protocol for scheduling
354	   between different implementations;

356	   [IMIP] specifies an Internet email binding for [ITIP].

358	   This memo does not attempt to repeat the specification of concepts or
359	   definitions from these other memos. Where possible, references are
360	   made to the memo that provides for the specification of these
361	   concepts or definitions.

363	2.3 International Considerations

365	   In the rest of this document, descriptions of characters are of the
366	   form "character name (codepoint)", where "codepoint" is from the US-
367	   ASCII character set. The "character name" is the authoritative
368	   description; (codepoint) is a reference to that character in US-
369	   ASCII or US-ASCII compatible sets (for example the ISO-8859-x family,
370	   UTF-8, ISO-2022-xx, KOI8-R). If a non-US-ASCII compatible character
371	   set is used, appropriate code-point from that character set must be
372	   chosen instead. Use of non-US-ASCII-compatible character sets is NOT
373	   recommended.

375	3  Registration Information

377	   The Calendaring and Scheduling Core Object Specification is intended
378	   for use as a MIME content type. However, the implementation of the
379	   memo is in no way limited solely as a MIME content type.

381	3.1 Content Type

383	   The following text is intended to register this memo as the MIME
384	   content type "text/calendar".

386	     To: ietf-types@uninett.no

388	     Subject: Registration of MIME content type text/calendar.

390	     MIME media type name: text

392	     MIME subtype name: calendar

394	3.2 Parameters

396	   Required parameters: none

398	   Optional parameters: charset, method, component and optinfo

400	   The "charset" parameter is defined in [RFC 2046] for other body
401	   parts. It is used to identify the default character set used within
402	   the body part.

404	   The "method" parameter is used to convey the iCalendar object method
405	   or transaction semantics for the calendaring and scheduling
406	   information. It also is an identifier for the restricted set of
407	   properties and values that the iCalendar object consists of. The
408	   parameter is to be used as a guide for applications interpreting the
409	   information contained within the body part. It SHOULD NOT be used to
410	   exclude or require particular pieces of information unless the
411	   identified method definition specifically calls for this behavior.
412	   Unless specifically forbidden by a particular method definition, a
413	   text/calendar content type can contain any set of properties
414	   permitted by the Calendaring and Scheduling Core Object
415	   Specification. The "method" parameter MUST be the same value as that
416	   specified in the "METHOD" component property in the iCalendar object.
417	   If one is present, the other must also be present.

419	   The value for the "method" parameter is defined as follows:

421	        method  = 1*(ALPHA / DIGIT / "-")
422	        ; IANA registered iCalendar object method

424	   The "component" parameter conveys the type of iCalendar calendar
425	   component within the body part. If the iCalendar object contains more
426	   than one calendar component type, then multiple component parameters
427	   MUST be specified.

429	   The value for the "component" parameter is defined as follows:

431	        component       = ("VEVENT" / "VTODO" / "VJOURNAL" / "VFREEBUSY"
432	                        / "VTIMEZONE" / x-name / iana-token)
433	   The "optinfo" parameter conveys optional information about the
434	   iCalendar object within the body part. This parameter can only
435	   specify semantics already specified by the iCalendar object and that
436	   can be otherwise determined by parsing the body part. In addition,
437	   the optional information specified by this parameter MUST be
438	   consistent with that information specified by the iCalendar object.
439	   For example, it can be used to convey the "Attendee" response status
440	   to a meeting request. The parameter value consists of a string value.
441	   The parameter can be specified multiple times.

443	   This parameter MAY only specify semantics already specified by the
444	   iCalendar object and that can be otherwise determined by parsing the
445	   body part.

447	   The value for the "optinfo" parameter is defined as follows:

449	        optinfo = infovalue / qinfovalue

451	        infovalue       = iana-token / x-name

453	        qinfovalue      = DQUOTE (infovalue) DQUOTE

455	3.3 Content Header Fields

457	   Optional content header fields: Any header fields defined by [RFC
458	   2045].

460	3.4 Encoding Considerations

462	     This MIME content type can contain 8bit characters, so the use of
463	     quoted-printable or BASE64 MIME content-transfer-encodings might be
464	     necessary when iCalendar objects are transferred across protocols
465	     restricted to the 7bit repertoire. Note that a text valued property
466	     in the content entity can also have content encoding of special
467	     characters using a BACKSLASH character (US-ASCII decimal 92)
468	     escapement technique. This means that content values can end up
469	     encoded twice.

471	3.5 Security Considerations

473	   SPOOFING - - In this memo, the "Organizer" is the only person
474	   authorized to make changes to an existing "VEVENT", "VTODO",
475	   "VJOURNAL" calendar component and redistribute the updates to the
476	   "Attendees". An iCalendar object that maliciously changes or cancels
477	   an existing "VEVENT", "VTODO" or "VJOURNAL" or "VFREEBUSY" calendar
478	   component might be constructed by someone other than the "Organizer"
479	   and sent to the "Attendees". In addition in this memo, other than the
480	   "Organizer", an "Attendee" of a "VEVENT", "VTODO", "VJOURNAL"
481	   calendar component is the only other person authorized to update any
482	   parameter associated with their "ATTENDEE" property and send it to
483	   the "Organizer". An iCalendar object that maliciously changes the
484	   "ATTENDEE" parameters can be constructed by someone other than the
485	   real "Attendee" and sent to the "Organizer".

487	   PROCEDURAL ALARMS - - An iCalendar object can be created that
488	   contains a "VEVENT" and "VTODO" calendar component with "VALARM"
489	   calendar components. The "VALARM" calendar component can be of type
490	   PROCEDURE and can have an attachment containing some sort of
491	   executable program. Implementations that incorporate these types of
492	   alarms are subject to any virus or malicious attack that might occur
493	   as a result of executing the attachment.

495	   ATTACHMENTS - - An iCalendar object can include references to Uniform
496	   Resource Locators that can be programmed resources.

498	   Implementers and users of this memo should be aware of the network
499	   security implications of accepting and parsing such information. In
500	   addition, the security considerations observed by implementations of
501	   electronic mail systems should be followed for this memo.

503	3.6 Interoperability Considerations

505	   This MIME content type is intended to define a common format for
506	   conveying calendaring and scheduling information between different
507	   systems. It is heavily based on the earlier [VCAL] industry
508	   specification.

510	3.7 Applications Which Use This Media Type

512	   This content-type is designed for widespread use by Internet
513	   calendaring and scheduling applications. In addition, applications in
514	   the workflow and document management area might find this content-
515	   type applicable. The [ITIP] and [IMIP] Internet protocols directly
516	   use this content-type also. Future work on an Internet calendar
517	   access protocol will utilize this content-type too.

519	3.8 Additional Information

521	   This memo defines this content-type.

523	3.9 Magic Numbers

525	   None.

527	3.10    File Extensions

529	   The file extension of "ics" is to be used to designate a file
530	   containing (an arbitrary set of) calendaring and scheduling
531	   information consistent with this MIME content type.

533	   The file extension of "ifb" is to be used to designate a file
534	   containing free or busy time information consistent with this MIME
535	   content type.

537	   Macintosh file type codes: The file type code of "iCal" is to be used
538	   in Apple MacIntosh operating system environments to designate a file
539	   containing calendaring and scheduling information consistent with
540	   this MIME media type.

542	   The file type code of "iFBf" is to be used in Apple MacIntosh
543	   operating system environments to designate a file containing free or
544	   busy time information consistent with this MIME media type.

546	3.11    Contact for Further Information:

548	   Frank Dawson
549	   6544 Battleford Drive
550	   Raleigh, NC 27613-3502
551	   919-676-9515 (Telephone)
552	   919-676-9564 (Data/Facsimile)
553	   Frank_Dawson@Lotus.com (Internet Mail)

555	   Derik Stenerson
556	   One Microsoft Way
557	   Redmond, WA  98052-6399
558	   425-936-5522 (Telephone)
559	   425-936-7329 (Facsimile)
560	   deriks@microsoft.com (Internet Mail)

562	3.12    Intended Usage

564	   COMMON

566	3.13    Authors/Change Controllers

568	   Frank Dawson
569	   6544 Battleford Drive
570	   Raleigh, NC 27613-3502
571	   919-676-9515 (Telephone)
572	   919-676-9564 (Data/Facsimile)
573	   Frank_Dawson@Lotus.com (Internet Mail)

575	   Derik Stenerson
576	   One Microsoft Way
577	   Redmond, WA  98052-6399
578	   425-936-5522 (Telephone)
579	   425-936-7329 (Facsimile)
580	   deriks@microsoft.com (Internet Mail)

582	4  iCalendar Object Specification

584	   The following sections define the details of a Calendaring and
585	   Scheduling Core Object Specification. This information is intended to
586	   be an integral part of the MIME content type registration. In
587	   addition, this information can be used independent of such content
588	   registration. In particular, this memo has direct applicability for
589	   use as a calendaring and scheduling exchange format in file-, memory-
590	   or network-based transport mechanisms.

592	4.1 Content Lines

594	   The iCalendar object is organized into individual lines of text,
595	   called content lines. Content lines are delimited by a line break,
596	   which is a CRLF sequence (US-ASCII decimal 13, followed by US-ASCII
597	   decimal 10).

599	   Lines of text SHOULD NOT be longer than 75 octets, excluding the line
600	   break. Long content lines SHOULD be split into a multiple line
601	   representations using a line "folding" technique. That is, a long
602	   line can be split between any two characters by inserting a CRLF
603	   immediately followed by a single linear white space character (i.e.,
604	   SPACE, US-ASCII decimal 32 or HTAB, US-ASCII decimal 9). Any sequence
605	   of CRLF followed immediately by a single linear white space character
606	   is ignored (i.e., removed) when processing the content type.

608	   For example the line:

610	     DESCRIPTION:This is a long description that exists on a long line.

612	   Can be represented as:

614	     DESCRIPTION:This is a lo
615	      ng description
616	       that exists on a long line.

618	   The process of moving from this folded multiple line representation
619	   to its single line representation is called "unfolding". Unfolding is
620	   accomplished by removing the CRLF character and the linear white
621	   space character that immediately follows.

623	   When parsing a content line, folded lines must first be unfolded
624	   according to the unfolding procedure described above. When generating
625	   a content line, lines longer than 75 octets SHOULD be folded
626	   according to the folding procedure described above.

628	   The content information associated with an iCalendar object is
629	   formatted using a syntax similar to that defined by [MIME DIR]. That
630	   is, the content information consists of one or more CRLF-separated
631	   content lines.

633	   The following notation defines the defines the lines of content in an
634	   iCalendar object:

636	     contentline        = name *(";" param ) ":" value CRLF
637	        ; This ABNF is just a general definition for an initial parsing
638	        ; of the content line into its property name, parameter list,
639	        ; and value string

641	     ; When parsing a content line, folded lines must first
642	        ; be unfolded according to the unfolding procedure
643	        ; described above. When generating a content line, lines
644	        ; longer than 75 octets SHOULD be folded according to
645	        ; the folding procedure described above.

647	     name               = x-name / iana-token
648	     iana-token = 1*(ALPHA / DIGIT / "-")
649	     ; iCalendar identifier registered with IANA

651	     x-name             = "X-" [vendorid "-"] 1*(ALPHA / DIGIT / "-")
652	     ; Reservered for experimental use.  Not intended for use in
653	     ; released products.

655	     vendorid   = 3*(ALPHA / DIGIT)     ;Vendor identification

657	     param              = param-name "=" param-value
658	                          *("," param-value)
659	        ; Each property defines the specific ABNF for the parameters
660	        ; allowed on the property. Refer to specific properties for
661	        ; precise parameter ABNF.

663	     param-name = iana-token / x-token

665	     param-value        = paramtext / quoted-string

667	     paramtext  = *SAFE-CHAR

669	     value      = *VALUE-CHAR

671	     quoted-string      = DQUOTE *QSAFE-CHAR DQUOTE

673	     NON-US-ASCII       = %x80-F8
674	     ; Use restricted by charset parameter
675	     ; on outer MIME object (UTF-8 preferred)

677	     QSAFE-CHAR = WSP / %x21 / %x23-7E / NON-US-ASCII
678	     ; Any character except CTLs and DQUOTE

680	     SAFE-CHAR  = WSP / %x21 / %x23-2B / %x2D-39 / %x3C-7E
681	                / NON-US-ASCII
682	     ; Any character except CTLs, DQUOTE, ";", ":", ","

684	     VALUE-CHAR = WSP / %x21-7E / NON-US-ASCII
685	     ; Any textual character

687	     CR = %x0D
688	     ; carriage return

690	     LF = %x0A
691	     ; line feed

693	     CRLF       = CR LF
694	     ; Internet standard newline

696	     CTL        = %x00-08 / %x0A-1F / %x7F
697	        ; Controls

699	     ALPHA      = %x41-5A / %x61-7A   ; A-Z / a-z
700	     DIGIT      = %x30-39
701	        ; 0-9

703	     DQUOTE     = %x22
704	        ; Quotation Mark

706	     WSP        = SPACE / HTAB

708	     SPACE      = %x20

710	     HTAB       = %x09

712	   The property value component of a content line has a format that is
713	   property specific. Refer to the section describing each property for
714	   a definition of this format.

716	   All names of properties, property parameters, enumerated property
717	   values and property parameter values are case-insensitive. However,
718	   all other property values are case-sensitive, unless otherwise
719	   stated.

721	4.1.1   List and Field Separators

723	   Some properties and parameters allow a list of values. Each value in
724	   a list of values MUST be separated by a COMMA character (US-ASCII
725	   decimal 44). There is no significance to the ordering of values in a
726	   list. For those parameter values (such as those that specify URI
727	   values) that are specified in quoted-strings, the individual quoted-
728	   strings are separated by a COMMA character (US-ASCII decimal 44).

730	   Some property values are defined in terms of multiple parts. These
731	   structured property values MUST have their value parts separated by a
732	   SEMICOLON character (US-ASCII decimal 59).

734	   Some properties allow a list of parameters. Each property parameter
735	   in a list of property parameters MUST be separated by a SEMICOLON
736	   character (US-ASCII decimal 59).

738	   Property parameters with values containing a COLON, a SEMICOLON or a
739	   COMMA character MUST be placed in quoted text.

741	   For example, in the following properties a SEMICOLON is used to
742	   separate property parameters and property value fields. A COMMA is
743	   used to separate values.

745	     ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT:MAILTO:
746	      jsmith@host.com

748	     RDATE;VALUE=DATE:19970304,19970504,19970704,19970904

750	4.1.2   Multiple Values

752	   Some properties defined in the iCalendar object can have multiple
753	   values. The general rule for encoding multi-valued items is to simply
754	   create a new content line for each value, including the property
755	   name. However, it should be noted that some properties support
756	   encoding multiple values in a single property by separating the
757	   values with a COMMA character (US-ASCII decimal 44). Individual
758	   property definitions should be consulted for determining whether a
759	   specific property allows multiple values and in which of these two
760	   forms.

762	4.1.3   Binary Content

764	   Binary content information in an iCalendar object SHOULD be
765	   referenced using a URI within a property value. That is the binary
766	   content information SHOULD be placed in an external MIME entity that
767	   can be referenced by a URI from within the iCalendar object. In
768	   applications where this is not feasible, binary content information
769	   can be included within an iCalendar object, but only after first
770	   encoding it into text using the "BASE64" encoding method defined in
771	   [RFC 2045]. Support for inline binary content SHOULD be restricted to
772	   those applications requirements that necessitate conveying the
773	   complete calendaring and scheduling information within a single
774	   iCalendar object. A property containing inline binary content
775	   information MUST specify the "ENCODING" property parameter. Binary
776	   content information placed external to the iCalendar object MUST be
777	   referenced by a uniform resource identifier (URI).

779	   The following example specifies an "ATTACH" property that references
780	   an attachment external to the iCalendar object with a URI reference:

782	     ATTACH:http://xyz.com/public/quarterly-report.doc

784	   The following example specifies an "ATTACH" property with inline
785	   binary encoded content information:

787	     ATTACH;ENCODING=BASE64;VALUE=BINARY:MIICajCCAdOgAwIBAgICBEUwD
788	      QYJKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjY
789	      XBlIENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvc
790	        <...remainder of "BASE64" encoded binary data...>

792	4.1.4   Character Set

794	   There is not a property parameter to declare the character set used
795	   in a property value. The default character set for an iCalendar
796	   object is UTF-8 as defined in [RFC 2279].

798	   The "charset" Content-Type parameter can be used in MIME transports
799	   to specify any other IANA registered character set.

801	4.2 Property Parameters

803	   A property can have attributes associated with it. These "property
804	   parameters" contain meta-information about the property or the
805	   property value. Property parameters are provided to specify such
806	   information as the location of an alternate text representation for a
807	   property value, the language of a text property value, the data type
808	   of the property value and other attributes.

810	   Property parameter values that contain the COLON (US-ASCII decimal
811	   58), SEMICOLON (US-ASCII decimal 59) or COMMA (US-ASCII decimal 44)
812	   character separators MUST be specified as quoted-string text values.
813	   Property parameter values MUST NOT contain the DOUBLE-QUOTE (US-ASCII
814	   decimal 22) character. The DOUBLE-QUOTE (US-ASCII decimal 22)
815	   character is used as a delimiter for parameter values that contain
816	   restricted characters or URI text. For example:

818	     DESCRIPTION;ALTREP="http://www.wiz.org":The Fall'98 Wild Wizards
819	       Conference - - Las Vegas, NV, USA

821	   Property parameter values that are not in quoted strings are case
822	   insensitive.

824	   The general property parameters defined by this memo are defined by
825	   the following notation:

827	     parameter  = altrepparam           ; Alternate text representation
828	                / cnparam               ; Common name
829	                / cutypeparam           ; Calendar user type
830	                / delfromparam          ; Delegator
831	                / deltoparam            ; Delegatee
832	                / dirparam              ; Directory entry
833	                / encodingparam         ; Inline encoding
834	                / fbtypeparam           ; Free/busy time type
835	                / languageparam         ; Language for text
836	                / memberparam           ; Group or list membership
837	                / partstatparam         ; Participation status
838	                / rangeparam            ; Recurrence identifier range
839	                / trigrelparam          ; Alarm trigger relationship
840	                / reltypeparam          ; Relationship type
841	                / roleparam             ; Participation role
842	                / rsvpparam             ; RSVP expectation
843	                / sentbyparam           ; Sent by
844	                / tzidparam             ; Reference to time zone object
845	                / valuetypeparam        ; Property value data type
846	                / ianaparam
847	        ; Some other IANA registered iCalendar parameter.
848	                / xparam
849	        ; A non-standard, experimental parameter.

851	     ianaparam  = iana-token "=" param-value *("," param-value)

853	     xparam     =x-name "=" param-value *("," param-value)

855	4.2.1   Alternate Text Representation

857	   Parameter Name: ALTREP

859	   Purpose: To specify an alternate text representation for the property
860	   value.

862	   Format Definition: The property parameter is defined by the following
863	   notation:

865	     altrepparam        = "ALTREP" "=" DQUOTE uri DQUOTE

867	   Description: The parameter specifies a URI that points to an
868	   alternate representation for a textual property value. A property
869	   specifying this parameter MUST also include a value that reflects the
870	   default representation of the text value. The individual URI
871	   parameter values MUST be specified in a quoted-string.

873	   Example:

875	     DESCRIPTION;ALTREP="CID:<part3.msg.970415T083000@host.com>":Project
876	       XYZ Review Meeting will include the following agenda items: (a)
877	       Market Overview, (b) Finances, (c) Project Management

879	   The "ALTREP" property parameter value might point to a "text/html"
880	   content portion.

882	     Content-Type:text/html
883	     Content-Id:<part3.msg.970415T083000@host.com>

885	     <html><body>
886	     <p><b>Project XYZ Review Meeting</b> will include the following
887	     agenda items:<li>Market
888	     Overview</li><li>Finances</li><li>Project Management</li></p>
889	     </html></body>

891	4.2.2   Common Name

893	   Parameter Name: CN

895	   Purpose: To specify the common name to be associated with the
896	   calendar user specified by the property.

898	   Format Definition: The property parameter is defined by the following
899	   notation:

901	     cnparam    = "CN" "=" param-value

903	   Description: This parameter can be specified on properties with a
904	   CAL-ADDRESS value type. The parameter specifies the common name to be
905	   associated with the calendar user specified by the property. The
906	   parameter value is text. The parameter value can be used for display
907	   text to be associated with the calendar address specified by the
908	   property.

910	   Example:

912	     ORGANIZER;CN="John Smith":MAILTO:jsmith@host.com
913	4.2.3   Calendar User Type

915	   Parameter Name: CUTYPE

917	   Purpose: To specify the type of calendar user specified by the
918	   property.

920	   Format Definition: The property parameter is defined by the following
921	   notation:

923	     cutypeparam        = "CUTYPE" "="
924	                         ("INDIVIDUAL"          ; An individual
925	                        / "GROUP"               ; A group of individuals
926	                        / "RESOURCE"            ; A physical resource
927	                        / "ROOM"                ; A room resource
928	                        / "UNKNOWN"             ; Otherwise not known
929	                        / x-name                ; Experimental type
930	                        / iana-token)           ; Other IANA registered
931	                                                ; type
932	     ; Default is INDIVIDUAL

934	   Description: This parameter can be specified on properties with a
935	   CAL-ADDRESS value type. The parameter identifies the type of calendar
936	   user specified by the property. If not specified on a property that
937	   allows this parameter, the default is INDIVIDUAL.

939	   Example:

941	     ATTENDEE;CUTYPE=GROUP:MAILTO:ietf-calsch@imc.org

943	4.2.4   Delegators

945	   Parameter Name: DELEGATED-FROM

947	   Purpose: To specify the calendar users that have delegated their
948	   participation to the calendar user specified by the property.

950	   Format Definition: The property parameter is defined by the following
951	   notation:

953	     delfromparam       = "DELEGATED-FROM" "=" DQUOTE cal-address DQUOTE
954	                          *("," DQUOTE cal-address DQUOTE)

956	   Description: This parameter can be specified on properties with a
957	   CAL-ADDRESS value type. This parameter can be specified on a property
958	   that has a value type of calendar address. This parameter specifies
959	   those calendar uses that have delegated their participation in a
960	   group scheduled event or to-do to the calendar user specified by the
961	   property. The value MUST be a MAILTO URI as defined in [RFC 1738].
962	   The individual URI parameter values MUST be specified in a quoted-
963	   string.

965	   Example:

967	     ATTENDEE;DELEGATED-FROM="MAILTO:jsmith@host.com":MAILTO:
968	      jdoe@host.com

970	4.2.5   Delegatees

972	   Parameter Name: DELEGATED-TO

974	   Purpose: To specify the calendar users whom the calendar user
975	   specified by the property has delegated participation to.

977	   Format Definition: The property parameter is defined by the following
978	   notation:

980	     deltoparam = "DELEGATED-TO" "=" DQUOTE cal-address DQUOTE
981	                  *("," DQUOTE cal-address DQUOTE)

983	   Description: This parameter can be specified on properties with a
984	   CAL-ADDRESS value type. This parameter specifies those calendar users
985	   whom have been delegated participation in a group scheduled event or
986	   to-do by the calendar user specified by the property. The value MUST
987	   be a MAILTO URI as defined in [RFC 1738]. The individual URI
988	   parameter values MUST be specified in a quoted-string.

990	   Example:

992	     ATTENDEE;DELEGATED-TO="MAILTO:jdoe@host.com","MAILTO:jqpublic@
993	      host.com":MAILTO:jsmith@host.com

995	4.2.6   Directory Entry Reference

997	   Parameter Name: DIR

999	   Purpose: To specify reference to a directory entry associated with
1000	   the calendar user specified by the property.

1002	   Format Definition: The property parameter is defined by the following
1003	   notation:

1005	     dirparam   = "DIR" "=" DQUOTE uri DQUOTE

1007	   Description: This parameter can be specified on properties with a
1008	   CAL-ADDRESS value type. The parameter specifies a reference to the
1009	   directory entry associated with the calendar user specified by the
1010	   property. The parameter value is a URI. The individual URI parameter
1011	   values MUST be specified in a quoted-string.

1013	   Example:

1015	     ORGANIZER;DIR="ldap://host.com:6666/o=eDABC%20Industries,c=3DUS??
1016	      (cn=3DBJim%20Dolittle)":MAILTO:jimdo@host1.com

1018	4.2.7   Inline Encoding

1020	   Parameter Name: ENCODING
1021	   Purpose: To specify an alternate inline encoding for the property
1022	   value.

1024	   Format Definition: The property parameter is defined by the following
1025	   notation:

1027	     encodingparam      = "ENCODING" "="
1028	                          ("8BIT"
1029	        ; "8bit" text encoding is defined in [RFC 2045]
1030	                        / "BASE64"
1031	        ; "BASE64" binary encoding format is defined in [RFC 2045]
1032	                        / iana-token
1033	        ; Some other IANA registered iCalendar encoding type
1034	                        / x-name)
1035	        ; A non-standard, experimental encoding type

1037	   Description: The property parameter identifies the inline encoding
1038	   used in a property value. The default encoding is "8BIT",
1039	   corresponding to a property value consisting of text. The "BASE64"
1040	   encoding type corresponds to a property value encoded using the
1041	   "BASE64" encoding defined in [RFC 2045].

1043	   If the value type parameter is ";VALUE=BINARY", then the inline
1044	   encoding parameter MUST be specified with the value
1045	   ";ENCODING=BASE64".

1047	   Example:

1049	     ATTACH;ENCODING=BASE64;VALUE=BINARY:MIICajCCAdOgAwIBAgICBEUwD
1050	      QYJKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjY
1051	      XBlIENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZvc
1052	        <...remainder of "BASE64" encoded binary data...>

1054	4.2.8   Free/Busy Time Type

1056	   Parameter Name: FBTYPE

1058	   Purpose: To specify the free or busy time type.

1060	   Format Definition: The property parameter is defined by the following
1061	   notation:

1063	     fbtypeparam        = "FBTYPE" "=" ("FREE" / "BUSY"
1064	                        / "BUSY-UNAVAILABLE" / "BUSY-TENTATIVE"
1065	                        / x-name
1066	        ; Some experimental iCalendar data type.
1067	                        / iana-token)
1068	        ; Some other IANA registered iCalendar data type.

1070	   Description: The parameter specifies the free or busy time type. The
1071	   value FREE indicates that the time interval is free for scheduling.
1072	   The value BUSY indicates that the time interval is busy because one
1073	   or more events have been scheduled for that interval. The value BUSY-
1074	   UNAVAILABLE indicates that the time interval is busy and that the
1075	   interval can not be scheduled. The value BUSY-TENTATIVE indicates
1076	   that the time interval is busy because one or more events have been
1077	   tentatively scheduled for that interval. If not specified on a
1078	   property that allows this parameter, the default is BUSY.

1080	   Example: The following is an example of this parameter on a FREEBUSY
1081	   property.

1083	     FREEBUSY;FBTYPE=BUSY:19980415T133000Z/19980415T170000Z

1085	4.2.9   Language

1087	   Parameter Name: LANGUAGE

1089	   Purpose: To specify the language for text values in a property or
1090	   property parameter.

1092	   Format Definition: The property parameter is defined by the following
1093	   notation:

1095	     languageparam =    "LANGUAGE" "=" language

1097	     language = <Text identifying a language, as defined in [RFC 1766]>

1099	   Description: This parameter can be specified on properties with a
1100	   text value type. The parameter identifies the language of the text in
1101	   the property or property parameter value. The value of the "language"
1102	   property parameter is that defined in [RFC 1766].

1104	   For transport in a MIME entity, the Content-Language header field can
1105	   be used to set the default language for the entire body part.
1106	   Otherwise, no default language is assumed.

1108	   Example:

1110	     SUMMARY;LANGUAGE=us-EN:Company Holiday Party

1112	     LOCATION;LANGUAGE=en:Germany
1113	     LOCATION;LANGUAGE=no:Tyskland

1115	   The following example makes use of the Quoted-Printable encoding in
1116	   order to represent non-ASCII characters.

1118	     LOCATION;LANGUAGE=da:K=F8benhavn
1119	     LOCATION;LANGUAGE=en:Copenhagen

1121	4.2.10  Group or List Membership

1123	   Parameter Name: MEMBER

1125	   Purpose: To specify the group or list membership of the calendar user
1126	   specified by the property.

1128	   Format Definition: The property parameter is defined by the following
1129	   notation:

1131	     memberparam        = "MEMBER" "=" DQUOTE cal-address DQUOTE
1132	                          *("," DQUOTE cal-address DQUOTE)

1134	   Description: This parameter can be specified on properties with a
1135	   CAL-ADDRESS value type. The parameter identifies the groups or list
1136	   membership for the calendar user specified by the property. The
1137	   parameter value either a single calendar address in a quoted-string
1138	   or a COMMA character (US-ASCII decimal 44) list of calendar
1139	   addresses, each in a quoted-string. The individual calendar address
1140	   parameter values MUST be specified in a quoted-string.

1142	   Example:

1144	     ATTENDEE;MEMBER="MAILTO:ietf-calsch@imc.org":MAILTO:jsmith@host.com

1146	     ATTENDEE;MEMBER="MAILTO:projectA@host.com","MAILTO:projectB@host.
1147	      com":MAILTO:janedoe@host.com

1149	4.2.11  Participation Status

1151	   Parameter Name: PARTSTAT

1153	   Purpose: To specify the participation status for the calendar user
1154	   specified by the property.

1156	   Format Definition: The property parameter is defined by the following
1157	   notation:

1159	     partstatparam      = "PARTSTAT" "="
1160	                         ("NEEDS-ACTION"        ; Event needs action
1161	                        / "ACCEPTED"            ; Event accepted
1162	                        / "DECLINED"            ; Event declined
1163	                        / "TENTATIVE"           ; Event tentatively
1164	                                                ; accepted
1165	                        / "DELEGATED"           ; Event delegated
1166	                        / x-name                ; Experimental status
1167	                        / iana-token)           ; Other IANA registered
1168	                                                ; status
1169	     ; These are the participation statuses for a "VEVENT". Default is
1170	     ; NEEDS-ACTION

1172	     partstatparam      /= "PARTSTAT" "="
1173	                         ("NEEDS-ACTION"        ; To-do needs action
1174	                        / "ACCEPTED"            ; To-do accepted
1175	                        / "DECLINED"            ; To-do declined
1176	                        / "TENTATIVE"           ; To-do tentatively
1177	                                                ; accepted
1178	                        / "DELEGATED"           ; To-do delegated
1179	                        / "COMPLETED"           ; To-do completed.
1180	                                                ; COMPLETED property has
1181	                                                ;date/time completed.

1183	                        / "IN-PROCESS"          ; To-do in process of
1184	                                                ; being completed
1185	                        / x-name                ; Experimental status
1186	                        / iana-token)           ; Other IANA registered
1187	                                                ; status
1188	     ; These are the participation statuses for a "VTODO". Default is
1189	     ; NEEDS-ACTION

1191	     partstatparam      /= "PARTSTAT" "="
1192	                         ("NEEDS-ACTION"        ; Journal needs action
1193	                        / "ACCEPTED"            ; Journal accepted
1194	                        / "DECLINED"            ; Journal declined
1195	                        / x-name                ; Experimental status
1196	                        / iana-token)           ; Other IANA registered
1197	                                                ; status
1198	     ; These are the participation statuses for a "VJOURNAL". Default is
1199	     ; NEEDS-ACTION

1201	4.2.12  Recurrence Identifier Range

1203	   Parameter Name: RANGE

1205	   Purpose: To specify the effective range of recurrence instances from
1206	   the instance specified by the recurrence identifier specified by the
1207	   property.

1209	   Format Definition: The property parameter is defined by the following
1210	   notation:

1212	     rangeparam = "RANGE" "=" ("THISANDPRIOR"
1213	        ; To specify all instances prior to the recurrence identifier
1214	                / "THISANDFUTURE")
1215	        ; To specify the instance specified by the recurrence identifier
1216	        ; and all subsequent recurrence instances

1218	   Description: The parameter can be specified on a property that
1219	   specifies a recurrence identifier. The parameter specifies the
1220	   effective range of recurrence instances that is specified by the
1221	   property. The effective range is from the recurrence identified
1222	   specified by the property. If this parameter is not specified an
1223	   allowed property, then the default range is the single instance
1224	   specified by the recurrence identifier value of the property. The
1225	   parameter value can be "THISANDPRIOR" to indicate a range defined by
1226	   the recurrence identified value of the property and all prior
1227	   instances. The parameter value can also be "THISANDFUTURE" to
1228	   indicate a range defined by the recurrence identifier and all
1229	   subsequent instances.

1231	   Example:

1233	     RECURRENCE-ID;RANGE=THISANDPRIOR:19980401T133000Z
1234	4.2.13  Alarm Trigger Relationship

1236	   Parameter Name: RELATED

1238	   Purpose: To specify the relationship of the alarm trigger with
1239	   respect to the start or end of the calendar component.

1241	   Format Definition: The property parameter is defined by the following
1242	   notation:

1244	     trigrelparam       = "RELATED" "="
1245	                         ("START"       ; Trigger off of start
1246	                        / "END")        ; Trigger off of end

1248	   Description: The parameter can be specified on properties that
1249	   specify an alarm trigger with a DURATION value type. The parameter
1250	   specifies whether the alarm will trigger relative to the start or end
1251	   of the calendar component. The parameter value START will set the
1252	   alarm to trigger off the start of the calendar component; the
1253	   parameter value END will set the alarm to trigger off the end of the
1254	   calendar component. If the parameter is not specified on an allowable
1255	   property, then the default is START.

1257	   Example:

1259	     TRIGGER;RELATED=END:PT5M

1261	4.2.14  Relationship Type

1263	   Parameter Name: RELTYPE

1265	   Purpose: To specify the type of hierarchical relationship associated
1266	   with the calendar component specified by the property.

1268	   Format Definition: The property parameter is defined by the following
1269	   notation:

1271	     reltypeparam       = "RELTYPE" "="
1272	                         ("PARENT"      ; Parent relationship. Default.
1273	                        / "CHILD"       ; Child relationship
1274	                        / "SIBLING      ; Sibling relationship
1275	                        / iana-token    ; Some other IANA registered
1276	                                        ; iCalendar relationship type
1277	                        / x-name)       ; A non-standard, experimental
1278	                                        ; relationship type

1280	   Description: This parameter can be specified on a property that
1281	   references another related calendar. The parameter specifies the
1282	   hierarchical relationship type of the calendar component referenced
1283	   by the property. The parameter value can be PARENT, to indicate that
1284	   the referenced calendar component is a superior of calendar
1285	   component; CHILD to indicate that the referenced calendar component
1286	   is a subordinate of the calendar component; SIBLING to indicate that
1287	   the referenced calendar component is a peer of the calendar
1288	   component. If this parameter is not specified on an allowable
1289	   property, the default relationship type is PARENT.

1291	   Example:

1293	     RELATED-TO;RELTYPE=SIBLING:<19960401-080045-4000F192713@host.com>

1295	   Description: This parameter can be specified on properties with a
1296	   CAL-ADDRESS value type. The parameter identifies the participation
1297	   status for the calendar user specified by the property value. The
1298	   parameter values differ depending on whether they are associated with
1299	   a group scheduled "VEVENT", "VTODO" or "VJOURNAL". The values MUST
1300	   match one of the values allowed for the given calendar component. If
1301	   not specified on a property that allows this parameter, the default
1302	   value is NEEDS-ACTION.

1304	   Example:

1306	     ATTENDEE;PARTSTAT=DECLINED:MAILTO:jsmith@host.com

1308	4.2.15  Participation Role

1310	   Parameter Name: ROLE

1312	   Purpose: To specify the participation role for the calendar user
1313	   specified by the property.

1315	   Format Definition: The property parameter is defined by the following
1316	   notation:

1318	     roleparam  = "ROLE" "="
1319	                 ("CHAIR"               ; Indicates chair of the
1320	                                        ; calendar entity
1321	                / "REQ-PARTICIPANT"     ; Indicates a participant whose
1322	                                        ; participation is required
1323	                / "OPT-PARTICIPANT"     ; Indicates a participant whose
1324	                                        ; participation is optional
1325	                / "NON-PARTICIPANT"     ; Indicates a participant who is
1326	                                        ; copied for information
1327	                                        ; purposes only
1328	                / x-name                ; Experimental role
1329	                / iana-token)           ; Other IANA role
1330	     ; Default is REQ-PARTICIPANT

1332	   Description: This parameter can be specified on properties with a
1333	   CAL-ADDRESS value type. The parameter specifies the participation
1334	   role for the calendar user specified by the property in the group
1335	   schedule calendar component. If not specified on a property that
1336	   allows this parameter, the default value is REQ-PARTICIPANT.

1338	   Example:

1340	     ATTENDEE;ROLE=CHAIR:MAILTO:mrbig@host.com
1341	4.2.16  RSVP Expectation

1343	   Parameter Name: RSVP

1345	   Purpose: To specify whether there is an expectation of a favor of a
1346	   reply from the calendar user specified by the property value.

1348	   Format Definition: The property parameter is defined by the following
1349	   notation:

1351	     rsvpparam = "RSVP" "=" ("TRUE" / "FALSE")
1352	     ; Default is FALSE

1354	   Description: This parameter can be specified on properties with a
1355	   CAL-ADDRESS value type. The parameter identifies the expectation of a
1356	   reply from the calendar user specified by the property value. This
1357	   parameter is used by the "Organizer" to request a participation
1358	   status reply from an "Attendee" of a group scheduled event or to-do.
1359	   If not specified on a property that allows this parameter, the
1360	   default value is FALSE.

1362	   Example:

1364	     ATTENDEE;RSVP=TRUE:MAILTO:jsmith@host.com

1366	4.2.17  Sent By

1368	   Parameter Name: SENT-BY

1370	   Purpose: To specify the calendar user that is acting on behalf of the
1371	   calendar user specified by the property.

1373	   Format Definition: The property parameter is defined by the following
1374	   notation:

1376	     sentbyparam        = "SENT-BY" "=" DQUOTE cal-address DQUOTE

1378	   Description: This parameter can be specified on properties with a
1379	   CAL-ADDRESS value type. The parameter specifies the calendar user
1380	   that is acting on behalf of the calendar user specified by the
1381	   property. The parameter value MUST be a MAILTO URI as defined in [RFC
1382	   1738]. The individual URI parameter values MUST be specified in a
1383	   quoted-string.

1385	   Example:

1387	     ORGANIZER;SENT-BY:"MAILTO:sray@host.com":MAILTO:jsmith@host.com

1389	4.2.18  Time Zone Identifier

1391	   Parameter Name: TZID

1393	   Purpose: To specify the identifier for the time zone definition for a
1394	   time component in the property value.

1396	   Format Definition: This property parameter is defined by the
1397	   following notation:

1399	     tzidparam  = "TZID" "=" [tzidprefix] paramtext CRLF

1401	     tzidprefix = "/"

1403	   Description: The parameter MUST be specify on the "DTSTART", "DTEND",
1404	   "DUE", "EXDATE" and "RDATE" properties when either a DATE-TIME or
1405	   TIME value type is specified and when the value is not either a UTC
1406	   or a "floating" time. This property parameter specifies a text value
1407	   which uniquely identifies the "VTIMEZONE" calendar component to be
1408	   used when evaluating the time portion of the property. The value of
1409	   the TZID property parameter will be equal to the value of the TZID
1410	   property for the matching time zone definition. An individual
1411	   "VTIMEZONE" calendar component MUST be specified for each unique
1412	   "TZID" parameter value specified in the iCalendar object.

1414	   The parameter MUST be specified on properties with a DATE-TIME value
1415	   if the DATE-TIME is not either a UTC or a "floating" time.

1417	   The presence of the SOLIDUS character (US-ASCII decimal 47) as a
1418	   prefix, indicates that this TZID represents a unique ID in a globally
1419	   defined time zone registry (when such registry is defined).

1421	   The following are examples of this property parameter:

1423	     DTSTART;TZID=America-New_York:19980119T020000

1425	     DTEND;TZID=America-New_York:19980119T030000

1427	   The TZID property parameter MUST NOT be applied to DATE-TIME or TIME
1428	   properties whose time values are specified in UTC.

1430	   The use of local time in a DATE-TIME or TIME value without the TZID
1431	   property parameter is to be interpreted as a local time value,
1432	   regardless of the existence of "VTIMEZONE" calendar components in the
1433	   iCalendar object.

1435	   For more information see the sections on the data types DATE-TIME and
1436	   TIME.

1438	4.2.19  Value Data Types

1440	   Parameter Name: VALUE

1442	   Purpose: To explicitly specify the data type format for a property
1443	   value.

1445	   Format Definition: The "VALUE" property parameter is defined by the
1446	   following notation:

1448	     valuetypeparam = "VALUE" "=" valuetype
1449	     valuetype  = ("BINARY"
1450	                / "BOOLEAN"
1451	                / "CAL-ADDRESS"
1452	                / "DATE"
1453	                / "DATE-TIME"
1454	                / "DURATION"
1455	                / "FLOAT"
1456	                / "INTEGER"
1457	                / "PERIOD"
1458	                / "RECUR"
1459	                / "TEXT"
1460	                / "TIME"
1461	                / "URI"
1462	                / "UTC-OFFSET"
1463	                / x-name
1464	                ; Some experimental iCalendar data type.
1465	                / iana-token)
1466	                ; Some other IANA registered iCalendar data type.

1468	   Description: The parameter specifies the data type and format of the
1469	   property value. The property values MUST be of a single value type.
1470	   For example, a "RDATE" property cannot have a combination of DATE-
1471	   TIME and TIME value types.

1473	   If the property's value is the default value type, then this
1474	   parameter need not be specified. However, if the property's default
1475	   value type is overridden by some other allowable value type, then
1476	   this parameter MUST be specified.

1478	4.3 Property Value Data Types

1480	   The properties in an iCalendar object are strongly typed. The
1481	   definition of each property restricts the value to be one of the
1482	   value data types, or simply value types, defined in this section. The
1483	   value type for a property will either be specified implicitly as the
1484	   default value type or will be explicitly specified with the "VALUE"
1485	   parameter. If the value type of a property is one of the alternate
1486	   valid types, then it MUST be explicitly specified with the "VALUE"
1487	   parameter.

1489	4.3.1   Binary

1491	   Value Name: BINARY

1493	   Purpose: This value type is used to identify properties that contain
1494	   a character encoding of inline binary data. For example, an inline
1495	   attachment of an object code might be included in an iCalendar
1496	   object.

1498	   Formal Definition: The value type is defined by the following
1499	   notation:

1501	     binary     = *(4b-char) [b-end]
1502	     ; A "BASE64" encoded character string, as defined by [RFC 2045].

1504	     b-end      = (2b-char "==") / (3b-char "=")

1506	     b-char = ALPHA / DIGIT / "+" / "/"

1508	   Description: Property values with this value type MUST also include
1509	   the inline encoding parameter sequence of ";ENCODING=BASE64". That
1510	   is, all inline binary data MUST first be character encoded using the
1511	   "BASE64" encoding method defined in [RFC 2045]. No additional content
1512	   value encoding (i.e., BACKSLASH character encoding) is defined for
1513	   this value type.

1515	   Example: The following is an abridged example of a "BASE64" encoded
1516	   binary value data.

1518	     ATTACH;VALUE=BINARY;ENCODING=BASE64:MIICajCCAdOgAwIBAgICBEUwDQY
1519	      JKoZIhvcNAQEEBQAwdzELMAkGA1UEBhMCVVMxLDAqBgNVBAoTI05ldHNjYXBlI
1520	      ENvbW11bmljYXRpb25zIENvcnBvcmF0aW9uMRwwGgYDVQQLExNJbmZv
1521	        <...remainder of "BASE64" encoded binary data...>

1523	4.3.2   Boolean

1525	   Value Name: BOOLEAN

1527	   Purpose: This value type is used to identify properties that contain
1528	   either a "TRUE" or "FALSE" Boolean value.

1530	   Formal Definition: The value type is defind by the following
1531	   notation:

1533	     boolean    = "TRUE" / "FALSE"

1535	   Description: These values are case insensitive text. No additional
1536	   content value encoding (i.e., BACKSLASH character encoding) is
1537	   defined for this value type.

1539	   Example: The following is an example of a hypothetical property that
1540	   has a BOOLEAN value type:

1542	   GIBBERISH:TRUE

1544	4.3.3   Calendar User Address

1546	   Value Name: CAL-ADDRESS

1548	   Purpose: This value type is used to identify properties that contain
1549	   a calendar user address.

1551	   Formal Definition: The value type is as defined by the following
1552	   notation:

1554	     cal-address        = uri

1556	   Description: The value is a URI as defined by [RFC 1738] or any other
1557	   IANA registered form for a URI. When used to address an Internet
1558	   email transport address for a calendar user, the value MUST be a
1559	   MAILTO URI, as defined by [RFC 1738]. No additional content value
1560	   encoding (i.e., BACKSLASH character encoding) is defined for this
1561	   value type.

1563	   Example:

1565	     ATTENDEE:MAILTO:jane_doe@host.com

1567	4.3.4   Date

1569	   Value Name: DATE

1571	   Purpose: This value type is used to identify values that contain a
1572	   calendar date.

1574	   Formal Definition: The value type is defined by the following
1575	   notation:

1577	     date               = date-value

1579	     date-value         = date-fullyear date-month date-mday
1580	     date-fullyear      = 4DIGIT
1581	     date-month         = 2DIGIT        ;01-12
1582	     date-mday          = 2DIGIT        ;01-28, 01-29, 01-30, 01-31
1583	                                        ;based on month/year

1585	   Description: If the property permits, multiple "date" values can be
1586	   specified using a COMMA character (US-ASCII decimal 44) separator
1587	   character. The format for the value type is expressed as the [ISO
1588	   8601] complete representation, basic format for a calendar date. The
1589	   textual format specifies a four-digit year, two-digit month, and two-
1590	   digit day of the month. There are no separator characters between the
1591	   year, month and day component text.

1593	   No additional content value encoding (i.e., BACKSLASH character
1594	   encoding) is defined for this value type.

1596	   Example: The following represents July 14, 1997:

1598	     19970714

1600	4.3.5   Date-Time

1602	   Value Name: DATE-TIME

1604	   Purpose: This value type is used to identify values that specify a
1605	   precise calendar date and time of day.

1607	   Formal Definition: The value type is defined by the following
1608	   notation:

1610	     date-time  = date "T" time ;As specified in the date and time
1611	                                ;value definitions
1612	   Description: If the property permits, multiple "date-time" values MAY
1613	   be specified using a COMMA character (US-ASCII decimal 44) separator
1614	   character. No additional content value encoding (i.e., BACKSLASH
1615	   character encoding) is defined for this value type.

1617	   The "DATE-TIME" data type is used to identify values that contain a
1618	   precise calendar date and time of day. The format is based on the
1619	   [ISO 8601] complete representation, basic format for a calendar date
1620	   and time of day. The text format is a concatenation of the "date",
1621	   followed by the LATIN CAPITAL LETTER T character (US-ASCII decimal
1622	   84) time designator, followed by the "time" format.

1624	   The "DATE-TIME" data type expresses time values in three forms:

1626	   The form of date and time with UTC offset MUST NOT be used. For
1627	   example, the following is not valid for a date-time value:

1629	     DTSTART:19980119T230000-0800       ;Invalid time format

1631	   FORM #1: DATE WITH LOCAL TIME

1633	   The date with local time form is simply a date-time value that does
1634	   not contain the UTC designator nor does it reference a time zone. For
1635	   example, the following represents Janurary 18, 1998, at 11 PM:

1637	     DTSTART:19980118T230000

1639	   Date-time values of this type are said to be "floating" and are not
1640	   bound to any time zone in particular. They are used to represent the
1641	   same hour, minute, and second value regardless of which time zone is
1642	   currently being observed. For example, an event can be defined that
1643	   indicates that an individual will be busy from 11:00 AM to 1:00 PM
1644	   every day, no matter which time zone the person is in. In these
1645	   cases, a local time can be specified. The recipient of an iCalendar
1646	   object with a property value consisting of a local time, without any
1647	   relative time zone information, should interpret the value as being
1648	   fixed to whatever time zone the ATTENDEE is in at any given moment.
1649	   This means that two ATTENDEEs, in different time zones, receiving the
1650	   same event definition as a floating time, may be participating in the
1651	   event at different actual times. Floating time should only be used
1652	   where that is the reasonable behavior.

1654	   In most cases, a fixed time is desired. To properly communicate a
1655	   fixed time in a property value, either UTC time or local time with
1656	   time zone reference MUST be specified.

1658	   The use of local time in a DATE-TIME value without the TZID property
1659	   parameter is to be interpreted as floating time, regardless of the
1660	   existence of "VTIMEZONE" calendar components in the iCalendar object.

1662	   FORM #2: DATE WITH UTC TIME

1664	   The date with UTC time, or absolute time, is identified by a LATIN
1665	   CAPITAL LETTER Z suffix character (US-ASCII decimal 90), the UTC
1666	   designator, appended to the time value. For example, the following
1667	   represents January 19, 1998, at 0700 UTC:

1669	     DTSTART:19980119T070000Z

1671	   The TZID property parameter MUST NOT be applied to DATE-TIME
1672	   properties whose time values are specified in UTC.

1674	   FORM #3: DATE WITH LOCAL TIME AND TIME ZONE REFERENCE

1676	   The date and local time with reference to time zone information is
1677	   identified by the use the TZID property parameter to reference the
1678	   appropriate time zone definition. TZID is discussed in detail in the
1679	   section on Time Zone. For example, the following represents 2 AM in
1680	   New York on Janurary 19, 1998:

1682	          DTSTART;TZID=America-New_York:19980119T020000

1684	   Example: The following represents July 14, 1997, at 1:30 PM in New
1685	   York City in each of the three time formats, using the "DTSTART"
1686	   property.

1688	     DTSTART:19970714T133000            ;Local time
1689	     DTSTART:19970714T173000Z           ;UTC time
1690	     DTSTART;TZID=America-NYC:19970714T133000   ;Local time and time
1691	                        ; zone reference

1693	   A time value MUST ONLY specify 60 seconds when specifying the
1694	   periodic "leap second" in the time value. For example:

1696	     COMPLETED:19970630T235960Z

1698	4.3.6   Duration

1700	   Value Name: DURATION

1702	   Purpose: This value type is used to identify properties that contain
1703	   a duration of time.

1705	   Formal Definition: The value type is defined by the following
1706	   notation:

1708	     duration   = (["+"] / "-") "P" (dur-date / dur-time / dur-week)

1710	     dur-date   = dur-day [dur-time]
1711	     dur-time   = "T" (dur-hour / dur-minute / dur-second)
1712	     dur-week   = 1*DIGIT "W"
1713	     dur-hour   = 1*DIGIT "H" [dur-minute]
1714	     dur-minute = 1*DIGIT "M" [dur-second]
1715	     dur-second = 1*DIGIT "S"
1716	     dur-day    = 1*DIGIT "D"

1718	   Description: If the property permits, multiple "duration" values can
1719	   be specified using a COMMA character (US-ASCII decimal 44) separator
1720	   character. The format is expressed as the [ISO 8601] basic format for
1721	   the duration of time. The format can represent durations in terms of
1722	   weeks, days, hours, minutes, and seconds.

1724	   No additional content value encoding (i.e., BACKSLASH character
1725	   encoding) are defined for this value type.

1727	   Example: A duration of 15 days, 5 hours and 20 seconds would be:

1729	     P15DT5H0M20S

1731	   A duration of 7 weeks would be:

1733	     P7W

1735	4.3.7   Float

1737	   Value Name: FLOAT

1739	   Purpose: This value type is used to identify properties that contain
1740	   a real value number value.

1742	   Formal Definition: The value type is defined by the following
1743	   notation:

1745	     float      = (["+"] / "-") 1*DIGIT ["." 1*DIGIT]

1747	   Description: If the property permits, multiple "float" values can be
1748	   specified using a COMMA character (US-ASCII decimal 44) separator
1749	   character.

1751	   No additional content value encoding (i.e., BACKSLASH character
1752	   encoding) is defined for this value type.

1754	   Example:

1756	     1000000.0000001
1757	     1.333
1758	     -3.14

1760	4.3.8   Integer

1762	   Value Name:INTEGER

1764	   Purpose: This value type is used to identify properties that contain
1765	   a signed integer value.

1767	   Formal Definition: The value type is defined by the following
1768	   notation:

1770	     integer    = (["+"] / "-") 1*DIGIT

1772	   Description: If the property permits, multiple "integer" values can
1773	   be specified using a COMMA character (US-ASCII decimal 44) separator
1774	   character. The valid range for "integer" is -2147483648 to
1775	   2147483647. If the sign is not specified, then the value is assumed
1776	   to be positive. If the property permits, multiple "integer" values
1777	   can be specified using a COMMA character (US-ASCII decimal 44)
1778	   separator character.

1780	   No additional content value encoding (i.e., BACKSLASH character
1781	   encoding) is defined for this value type.

1783	   Example:

1785	     1234567890
1786	     -1234567890
1787	     +1234567890
1788	     432109876

1790	4.3.9   Period of Time

1792	   Value Name: PERIOD

1794	   Purpose: This value type is used to identify values that contain a
1795	   precise period of time.

1797	   Formal Definition: The data type is defined by the following
1798	   notation:

1800	     period     = period-explicit / period-start

1802	     period-explicit = date-time "/" date-time
1803	     ; [ISO 8601] complete representation basic format for a period of
1804	     ; time consisting of a start and end. The start MUST be before the
1805	     ; end.

1807	     period-start = date-time "/" duration
1808	     ; [ISO 8601] complete representation basic format for a period of
1809	     ; time consisting of a start and positive duration of time.

1811	   Description: If the property permits, multiple "period" values can be
1812	   specified using a COMMA character (US-ASCII decimal 44) separator
1813	   character. There are two forms of a period of time. A period of time
1814	   is identified by its start and its end. This format is expressed as
1815	   the [ISO 8601] complete representation, basic format for "DATE-TIME"
1816	   start of the period, followed by a SOLIDUS character (US-ASCII
1817	   decimal 47), followed by the "DATE-TIME" of the end of the period.
1818	   The start of the period MUST be before the end of the period. A
1819	   period of time can also be defined by a start and a positive duration
1820	   of time. The format is expressed as the [ISO 8601] complete
1821	   representation, basic format for the "DATE-TIME" start of the period,
1822	   followed by a SOLIDUS character (US-ASCII decimal 47), followed by
1823	   the [ISO 8601] basic format for "DURATION" of the period.

1825	   Example: The period starting at 18:00:00 UTC, on January 1, 1997 and
1826	   ending at 07:00:00 UTC on January 2, 1997 would be:

1828	     19970101T180000Z/19970102T070000Z

1830	   The period start at 18:00:00 on January 1, 1997 and lasting 5 hours
1831	   and 30 minutes would be:

1833	     19970101T180000Z/PT5H30M

1835	   No additional content value encoding (i.e., BACKSLASH character
1836	   encoding) is defined for this value type.

1838	4.3.10  Recurrence Rule

1840	   Value Name: RECUR

1842	   Purpose: This value type is used to identify properties that contain
1843	   a recurrence rule specification.

1845	   Formal Definition: The value type is defined by the following
1846	   notation:

1848	     recur      = "FREQ"=freq
1849	                [(";" "UNTIL" "=" enddate) / (";" "COUNT" "=" 1*DIGIT)]
1850	                [";" "INTERVAL" "=" 1*DIGIT]
1851	                [";" "BYSECOND" "=" byseclist]
1852	                [";" "BYMINUTE" "=" byminlist]
1853	                [";" "BYHOUR" "=" byhrlist]
1854	                [";" "BYDAY" "=" bywdaylist]
1855	                [";" "BYMONTHDAY" "=" bymodaylist]
1856	                [";" "BYYEARDAY" "=" byyrdaylist]
1857	                [";" "BYWEEKNO" "=" bywknolist]
1858	                [";" "BYMONTH" "=" bymolist]
1859	                [";" "BYSETPOS" "=" bysplist]
1860	                [";" "WKST" "=" weekday)]
1861	                *(";" x-name "=" text)
1862	        ;Individual rule parts MUST only be specified once.
1863	        ;Rule parts need not be specified in particular any order.

1865	     freq       = "SECONDLY" / "MINUTELY" / "HOURLY" / "DAILY"
1866	                / "WEEKLY" / "MONTHLY" / "YEARLY"

1868	     enddate    = date
1869	     enddate    =/ date-time            ;An UTC value

1871	     byseclist  = seconds / ( seconds *("," seconds) )

1873	     seconds    = 1DIGIT / 2DIGIT       ;0 to 59

1875	     byminlist  = minutes / ( minutes *("," minutes) )

1877	     minutes    = 1DIGIT / 2DIGIT       ;0 to 59

1879	     byhrlist   = hour / ( hour *("," hour) )

1881	     hour       = 1DIGIT / 2DIGIT       ;0 to 23
1882	     bywdaylist = weekdaynum / ( weekdaynum *("," weekdaynum) )

1884	     weekdaynum = [([plus] ordwk / minus ordwk)] weekday

1886	     plus       = "+"

1888	     minus      = "-"

1890	     ordwk      = 1DIGIT / 2DIGIT       ;1 to 53

1892	     weekday    = "SU" / "MO" / "TU" / "WE" / "TH" / "FR" / "SA"
1893	     ;Corresponding to SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY,
1894	     ;FRIDAY, SATURDAY and SUNDAY days of the week.

1896	     bymodaylist = monthdaynum / ( monthdaynum *("," monthdaynum) )

1898	     monthdaynum = ([plus] ordmoday) / (minus ordmoday)

1900	     ordmoday   = 1DIGIT / 2DIGIT       ;1 to 31

1902	     byyrdaylist = yeardaynum / ( yeardaynum *("," yeardaynum) )

1904	     yeardaynum = ([plus] ordyrday) / (minus ordyrday)

1906	     ordyrday   = 1DIGIT / 2DIGIT / 3DIGIT      ;1 to 366

1908	     bywknolist = weeknum / ( weeknum *("," weeknum) )

1910	     weeknum    = ([plus] ordwk) / (minus ordwk)

1912	     bymolist   = monthnum / ( monthnum *("," monthnum) )

1914	     monthnum   = 1DIGIT / 2DIGIT       ;1 to 12

1916	     bysplist   = setposday / ( setposday *("," setposday) )

1918	     setposday  = yeardaynum

1920	   Description: If the property permits, multiple "recur" values can be
1921	   specified using a COMMA character (US-ASCII decimal 44) separator
1922	   character. The value type is a structured value consisting of a list
1923	   of one or more recurrence grammar parts. Each rule part is defined by
1924	   a NAME=VALUE pair. The rule parts are separated from each other by
1925	   the SEMICOLON character (US-ASCII decimal 59). The rule parts are not
1926	   ordered in any particular sequence. Individual rule parts MUST only
1927	   be specified once.

1929	   The FREQ rule part identifies the type of recurrence rule. This rule
1930	   part MUST be specified in the recurrence rule. Valid values include
1931	   SECONDLY, to specify repeating events based on an interval of a
1932	   second or more; MINUTELY, to specify repeating events based on an
1933	   interval of a minute or more; HOURLY, to specify repeating events
1934	   based on an interval of an hour or more; DAILY, to specify repeating
1935	   events based on an interval of a day or more; WEEKLY, to specify
1936	   repeating events based on an interval of a week or more; MONTHLY, to
1937	   specify repeating events based on an interval of a month or more; and
1938	   YEARLY, to specify repeating events based on an interval of a year or
1939	   more.

1941	   The INTERVAL rule part contains a positive integer representing how
1942	   often the recurrence rule repeats. The default value is "1" or every
1943	   second for a SECONDLY rule, or every minute for a MINUTELY rule,
1944	   every hour for an HOURLY rule, every day for a DAILY rule, every week
1945	   for a WEEKLY rule, every month for a MONTHLY rule and every year for
1946	   a YEARLY rule.

1948	   The UNTIL rule part defines a date-time value which bounds the
1949	   recurrence rule in an inclusive manner. If the value specified by
1950	   UNTIL is synchronized with the specified recurrence, this date or
1951	   date-time becomes the last instance of the recurrence. If specified
1952	   as a date-time value, then it MUST be specified in an UTC time
1953	   format. If not present, and the COUNT rule part is also not present,
1954	   the RRULE is considered to repeat forever.

1956	   The COUNT rule part defines the number of occurrences at which to
1957	   range-bound the recurrence. The "DTSTART" property value, if
1958	   specified, counts as the first occurrence.

1960	   The BYSECOND rule part specifies a COMMA character (US-ASCII decimal
1961	   44) separated list of seconds within a minute. Valid values are 0 to
1962	   59. The BYMINUTE rule part specifies a COMMA character (US-ASCII
1963	   decimal 44) separated list of minutes within an hour. Valid values
1964	   are 0 to 59. The BYHOUR rule part specifies a COMMA character (US-
1965	   ASCII decimal 44) separated list of hours of the day. Valid values
1966	   are 0 to 23.

1968	   The BYDAY rule part specifies a COMMA character (US-ASCII decimal 44)
1969	   separated list of days of the week; MO, indicates Monday; TU,
1970	   indicates Tuesday; WE, indicates Wednesday; TH, indicates Thursday;
1971	   FR, indicates Friday; SA, indicates Saturday; SU, indicates Sunday.

1973	   Each BYDAY value can also be preceded by a positive (+n) or negative
1974	   (-n) integer. If present, this indicates the nth occurrence of the
1975	   specific day within the MONTHLY or YEARLY RRULE. For example, within
1976	   a MONTHLY rule, +1MO (or simply 1MO) represents the first Monday
1977	   within the month, whereas -1MO represents the last Monday of the
1978	   month. If an integer modifier is not present, it means all days of
1979	   this type within the specified frequency. For example, within a
1980	   MONTHLY rule, MO represents all Mondays within the month.

1982	   The BYMONTHDAY rule part specifies a COMMA character (ASCII decimal
1983	   44) separated list of days of the month. Valid values are 1 to 31 or
1984	   -31 to -1. For example, -10 represents the tenth to the last day of
1985	   the month.

1987	    The BYYEARDAY rule part specifies a COMMA character (US-ASCII
1988	   decimal 44) separated list of days of the year. Valid values are 1 to
1989	   366 or -366 to -1. For example, -1 represents the last day of the
1990	   year (December 31st) and -306 represents the 306th to the last day of
1991	   the year (March 1st).

1993	   The BYWEEKNO rule part specifies a COMMA character (US-ASCII decimal
1994	   44) separated list of ordinals specifying weeks of the year. Valid
1995	   values are 1 to 53 or -53 to -1. This corresponds to weeks according
1996	   to week numbering as defined in [ISO 8601]. The first calendar week
1997	   of the year is the one that includes the first 4 days of the year. A
1998	   week is defined as a seven day period, starting on the day of the
1999	   week defined to be the week start (see WKST). This rule part is only
2000	   valid for YEARLY rules. For example, 3 represents the third week of
2001	   the year.

2003	        Note: Assuming a Monday week start, week 53 can only occur when
2004	        Thursday is January 1 or if it is a leap year and Wednesday is
2005	        January 1.

2007	   The BYMONTH rule part specifies a COMMA character (US-ASCII decimal
2008	   44) separated list of months of the year. Valid values are 1 to 12.

2010	   The WKST rule part specifies the day on which the workweek starts.
2011	   Valid values are MO, TU  WE                          ,   , TH, FR, SA and SU. This is significant
2012	   when a WEEKLY RRULE has an interval greater than 1, and a BYDAY rule
2013	   part is specified. This is also significant when in a YEARLY RRULE
2014	   when a BYWEEKNO rule part is specified. The default value is MO.

2016	   The BYSETPOS rule part specifies a COMMA character (US-ASCII decimal
2017	   44) separated list of values which corresponds to the nth occurrence
2018	   within the set of events specified by the rule. Valid values are 1 to
2019	   366 or -366 to -1. It MUST only be used in conjunction with another
2020	   Byxxx rule part. For example "the last work day of the month" could
2021	   be represented as:

2023	     RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-1

2025	   Each BYSETPOS value can include a positive (+n) or negative (-n)
2026	   integer. If present, this indicates the nth occurrence of the
2027	   specific occurrence within the set of events specified by the rule.

2029	   If BYxxx rule part values are found which are beyond the available
2030	   scope (ie, BYMONTHDAY=30 in February), they are simply ignored.

2032	   Information, not contained in the rule, necessary to determine the
2033	   various recurrence instance start time and dates are derived from the
2034	   Start Time (DTSTART) entry attribute. For example,
2035	   "FREQ=YEARLY;BYMONTH=1" doesn't specify a specific day within the
2036	   month or a time. This information would be the same as what is
2037	   specified for DTSTART.

2039	   BYxxx rule parts modify the recurrence in some manner. BYxxx rule
2040	   parts for a period of time which is the same or greater than the
2041	   frequency generally reduce or limit the number of occurrences of the
2042	   recurrence generated. For example, "FREQ=DAILY;BYMONTH=1" reduces the
2043	   number of recurrence instances from all days (if BYMONTH tag is not
2044	   present) to all days in January. BYxxx rule parts for a period of
2045	   time less than the frequency generally increase or expand the number
2046	   of occurrences of the recurrence. For example,
2047	   "FREQ=YEARLY;BYMONTH=1,2" increases the number of days within the
2048	   yearly recurrence set from 1 (if BYMONTH tag is not present) to 2.

2050	   If multiple BYxxx rule parts are specified, then after evaluating the
2051	   specified FREQ and INTERVAL rule parts, the BYxxx rule parts are
2052	   applied to the current set of evaluated occurrences in the following
2053	   order: BYMONTH, BYWEEKNO, BYYEARDAY, BYMONTHDAY, BYDAY, BYHOUR,
2054	   BYMINUTE, BYSECOND and BYSETPOS; then COUNT and UNTIL are evaluated.

2056	   Here is an example of evaluating multiple BYxxx rule parts.

2058	     DTSTART;TZID=US-Eastern:19970105T083000
2059	     RRULE:FREQ=YEARLY;INTERVAL=2;BYMONTH=1;BYDAY=SU;BYHOUR=8,9;
2060	      BYMINUTE=30

2062	   First, the "INTERVAL=2" would be applied to "FREQ=YEARLY" to arrive
2063	   at "every other year". Then, "BYMONTH=1" would be applied to arrive
2064	   at "every January, every other year". Then, "BYDAY=SU" would be
2065	   applied to arrive at "every Sunday in January, every other year".
2066	   Then, "BYHOUR=8,9" would be applied to arrive at "every Sunday in
2067	   January at 8 AM and 9 AM, every other year". Then, "BYMINUTE=30"
2068	   would be applied to arrive at "every Sunday in January at 8:30 AM and
2069	   9:30 AM, every other year". Then, lacking information from RRULE, the
2070	   second is derived from DTSTART, to end up in "every day in January at
2071	   8:30:00 AM and 9:30:00 AM, every other year". Similarly, if the
2072	   BYMINUTE, BYHOUR, BYDAY, BYMONTHDAY or BYMONTH rule part were
2073	   missing, the appropriate minute, hour, day or month would have been
2074	   retrieved from the "DTSTART" property.

2076	   No additional content value encoding (i.e., BACKSLASH character
2077	   encoding) is defined for this value type.

2079	   Example: The following is a rule which specifies 10 meetings which
2080	   occur every other day:

2082	     FREQ=DAILY;COUNT=10;INTERVAL=2

2084	   There are other examples specified in the "RRULE" specification.

2086	4.3.11  Text

2088	   Value Name: TEXT

2090	   Purpose This value type is used to identify values that contain human
2091	   readable text.

2093	   Formal Definition: If the character set is UTF-8, the value type is
2094	   defined by the following notation. This must be modified depending on
2095	   character sets. For example, the definition of TSAFE-CHAR includes
2096	   ESC for character sets that use ISO 2022 character set switching and
2097	   TSAFE-CHAR should not include NON-US-ASCII when the character set is
2098	   US-ASCII.

2100	     text       = *(TSAFE-CHAR / ":" / DQUOTE / ESCAPED-CHAR)
2101	     ; Folded according to description above

2103	     ESCAPED-CHAR = "\\" / "\;" / "\," / "\N" / "\n")
2104	        ; \\ encodes \, \N or \n encodes newline
2105	        ; \; encodes ;, \, encodes ,

2107	     TSAFE-CHAR = %x20-21 / %x23-2B / %x2D-39 / %x3C-5B
2108	                  %x5D-7E / NON-US-ASCII
2109	        ; Any character except CTLs not needed by the current
2110	        ; character set, DQUOTE, ";", ":", "\", ","

2112	   Description: If the property permits, multiple "text" values can be
2113	   specified using a COMMA character (US-ASCII decimal 44) separator
2114	   character.

2116	   The language in which the text is represented can be controlled by
2117	   the "LANGUAGE" property parameter.

2119	   An intentional formatted text line break MUST only be included in a
2120	   "TEXT" property value by representing the line break with the
2121	   character sequence of BACKSLASH (US-ASCII decimal 92), followed by a
2122	   LATIN SMALL LETTER N (US-ASCII decimal 110) or a LATIN CAPITAL LETTER
2123	   N (US-ASCII decimal 78), that is "\n" or "\N".

2125	   The "TEXT" property values may also contain special characters that
2126	   are used to signify delimiters, such as a COMMA character for lists
2127	   of values or a SEMICOLON character for structured values. In order to
2128	   support the inclusion of these special characters in "TEXT" property
2129	   values, they need to be escaped with a BACKSLASH character. A
2130	   BACKSLASH character (US-ASCII decimal 92) in a "TEXT" property value
2131	   MUST be escaped with another BACKSLASH character. A COMMA character
2132	   in a "TEXT" property value MUST be escaped with a BACKSLASH character
2133	   (US-ASCII decimal 92). A SEMICOLON character in a "TEXT" property
2134	   value MUST be escaped with a BACKSLASH character (US-ASCII decimal
2135	   92). However, a COLON character in a "TEXT" property value SHALL NOT
2136	   be escaped with a BACKSLASH character.Example: A multiple line value
2137	   of:

2139	     Project XYZ Final Review
2140	     Conference Room - 3B
2141	     Come Prepared.

2143	   would be represented as:

2145	     Project XYZ Final Review\n Conference Room - 3B\nCome Prepared.

2147	4.3.12  Time

2149	   Value Name: TIME
2150	   Purpose: This value type is used to identify values that contain a
2151	   time of day.

2153	   Formal Definition: The data type is defined by the following
2154	   notation:

2156	     time               = time-hour time-minute time-second [time-utc]

2158	     time-hour          = 2DIGIT        ;00-23
2159	     time-minute        = 2DIGIT        ;00-59
2160	     time-second        = 2DIGIT        ;00-60
2161	     ;The "60" value is used to account for "leap" seconds.

2163	     time-utc   = "Z"

2165	   Description: If the property permits, multiple "time" values can be
2166	   specified using a COMMA character (US-ASCII decimal 44) separator
2167	   character. No additional content value encoding (i.e., BACKSLASH
2168	   character encoding) is defined for this value type.

2170	   The "TIME" data type is used to identify values that contain a time
2171	   of day. The format is based on the [ISO 8601] complete
2172	   representation, basic format for a time of day. The text format
2173	   consists of a two-digit 24-hour of the day (i.e., values 0-23), two-
2174	   digit minute in the hour (i.e., values 0-59), and two-digit seconds
2175	   in the minute (i.e., values 0-60). The seconds value of 60 is only to
2176	   be used to account for "leap" seconds. Fractions of a second are not
2177	   supported by this format.

2179	   In parallel to the "DATE-TIME" definition above, the "TIME" data type
2180	   expresses time values in three forms:

2182	   The form of time with UTC offset MUST NOT be used. For example, the
2183	   following is NOT VALID for a time value:

2185	     230000-0800        ;Invalid time format

2187	   FORM #1 LOCAL TIME

2189	   The local time form is simply a time value that does not contain the
2190	   UTC designator nor does it reference a time zone. For example, 11:00
2191	   PM:

2193	     230000

2195	   Time values of this type are said to be "floating" and are not bound
2196	   to any time zone in particular. They are used to represent the same
2197	   hour, minute, and second value regardless of which time zone is
2198	   currently being observed. For example, an event can be defined that
2199	   indicates that an individual will be busy from 11:00 AM to 1:00 PM
2200	   every day, no matter which time zone the person is in. In these
2201	   cases, a local time can be specified. The recipient of an iCalendar
2202	   object with a property value consisting of a local time, without any
2203	   relative time zone information, should interpret the value as being
2204	   fixed to whatever time zone the ATTENDEE is in at any given moment.
2205	   This means that two ATTENDEEs may participate in the same event at
2206	   different UTC times; floating time should only be used where that is
2207	   reasonable behavior.

2209	   In most cases, a fixed time is desired. To properly communicate a
2210	   fixed time in a property value, either UTC time or local time with
2211	   time zone reference MUST be specified.

2213	   The use of local time in a TIME value without the TZID property
2214	   parameter is to be interpreted as a local time value, regardless of
2215	   the existence of "VTIMEZONE" calendar components in the iCalendar
2216	   object.

2218	   FORM #2: UTC TIME

2220	   UTC time, or absolute time, is identified by a LATIN CAPITAL LETTER Z
2221	   suffix character (US-ASCII decimal 90), the UTC designator, appended
2222	   to the time value. For example, the following represents 07:00 AM
2223	   UTC:

2225	     070000Z

2227	   The TZID property parameter MUST NOT be applied to TIME properties
2228	   whose time values are specified in UTC.

2230	   FORM #3: LOCAL TIME AND TIME ZONE REFERENCE

2232	   The local time with reference to time zone information form is
2233	   identified by the use the TZID property parameter to reference the
2234	   appropriate time zone definition. TZID is discussed in detail in the
2235	   section on Time Zone.

2237	   Example: The following represents 8:30 AM in New York in Winter, five
2238	   hours behind UTC, in each of the three formats using the "X-
2239	   TIMEOFDAY" non-standard property:

2241	     X-TIMEOFDAY:083000

2243	     X-TIMEOFDAY:133000Z

2245	     X-TIMEOFDAY;TZID=America-New York:083000

2247	4.3.13  URI

2249	   Value Name: URI

2251	   Purpose: This value type is used to identify values that contain a
2252	   uniform resource identifier (URI) type of reference to the property
2253	   value.

2255	   Formal Definition: The data type is defined by the following
2256	   notation:

2258	     uri        = <As defined by any IETF RFC>

2260	   Description: This data type might be used to reference binary
2261	   information, for values that are large, or otherwise undesirable to
2262	   include directly in the iCalendar object.

2264	   The URI value formats in RFC 1738, RFC 2111 and any other IETF
2265	   registered value format can be specified.

2267	   Any IANA registered URI format can be used. These include, but are
2268	   not limited to, those defined in RFC 1738 and RFC 2111.

2270	   When a property parameter value is a URI value type, the URI must be
2271	   specified as a quoted-string value.

2273	   No additional content value encoding (i.e., BACKSLASH character
2274	   encoding) is defined for this value type.

2276	   Example: The following is a URI for a network file:

2278	     http://host1.com/my-report.txt

2280	4.3.14  UTC Offset

2282	   Value Name: UTC-OFFSET

2284	   Purpose: This value type is used to identify properties that contain
2285	   an offset from UTC to local time.

2287	   Formal Definition: The data type is defined by the following
2288	   notation:

2290	     utc-offset = time-numzone  ;As defined above in time data type

2292	     time-numzone       = ("+" / "-") time-hour time-minute

2294	   Description: The PLUS SIGN character MUST be specified for positive
2295	   UTC offsets (i.e., ahead of UTC). The value of "-0000" is not
2296	   allowed.

2298	   No additional content value encoding (i.e., BACKSLASH character
2299	   encoding) is defined for this value type.

2301	   Example: The following are UTC offsets are given for standard time
2302	   for New York (five hours behind UTC) and Geneva (one hour ahead of
2303	   UTC):

2305	     -0500

2307	     +0100
2308	4.4 iCalendar Object

2310	   The Calendaring and Scheduling Core Object is a collection of
2311	   calendaring and scheduling information. Typically, this information
2312	   will consist of a single iCalendar object. However, multiple
2313	   iCalendar objects can be sequentially grouped together. The first
2314	   line and last line of the iCalendar object MUST contain a pair of
2315	   iCalendar object delimiter strings. The syntax for an iCalendar
2316	   object is as follows:

2318	     icalobject = "BEGIN" ":" "VCALENDAR" CRLF
2319	                  icalbody
2320	                  "END" ":" "VCALENDAR" CRLF [icalobject]

2322	   The following is a simple example of an iCalendar object:

2324	     BEGIN:VCALENDAR
2325	     VERSION:2.0
2326	     PRODID:-//hacksw/handcal//NONSGML v1.0//EN
2327	     BEGIN:VEVENT
2328	     DTSTART:19970714T170000Z
2329	     DTEND:19970715T035959Z
2330	     SUMMARY:Bastille Day Party
2331	     END:VEVENT
2332	     END:VCALENDAR

2334	4.5 Property

2336	   A property is the definition of an individual attribute describing a
2337	   calendar property or a calendar component. A property takes the form
2338	   defined by the "contentline" notation defined in section 4.1.1.

2340	   The following is an example of a property:

2342	     DTSTART:19960415T133000Z

2344	   This memo places no imposed ordering of properties within an
2345	   iCalendar object.

2347	   Property names, parameter names and enumerated parameter values are
2348	   case insensitive. For example, the property name "DUE" is the same as
2349	   "due" and "Due", DTSTART;TZID=Eastern:19980714T120000 is the same as
2350	   DtStart;TzID=Eastern:19980714T120000.

2352	4.6 Calendar Components

2354	   The body of the iCalendar object consists of a sequence of calendar
2355	   properties and one or more calendar components. The calendar
2356	   properties are attributes that apply to the calendar as a whole. The
2357	   calendar components are collections of properties that express a
2358	   particular calendar semantic. For example, the calendar component can
2359	   specify an event, a to-do, a journal entry, time zone information, or
2360	   free/busy time information, or an alarm.

2362	   The body of the iCalenar object is defined by the following notation:

2364	     icalbody   = calprops component

2366	     calprops   = [calscale] [method] prodid version *x-prop

2368	     component  = 1*(eventc / todoc / journalc / freebusyc /
2369	                / timezonec / iana-comp / x-comp)

2371	     iana-comp  = "BEGIN" ":" iana-token CRLF

2373	                  1*contentline

2375	                  "END" ":" iana-token CRLF

2377	     x-comp     = "BEGIN" ":" x-name CRLF

2379	                  1*contentline

2381	                  "END" ":" x-name CRLF

2383	   An iCalendar object must include the "PRODID" and "VERSION" calendar
2384	   properties. In addition, it must include at least one calendar
2385	   component. Special forms of iCalendar objects are possible to publish
2386	   just busy time (i.e., only a "VFREEBUSY" calendar component) or time
2387	   zone (i.e., only a "VTIMEZONE" calendar component) information. In
2388	   addition, a complex iCalendar object is possible that is used to
2389	   capture a complete snapshot of the contents of a calendar (e.g.,
2390	   composite of many different calendar components). More commonly, an
2391	   iCalendar object will consist of just a single "VEVENT", "VTODO" or
2392	   "VJOURNAL" calendar component.

2394	4.6.1   Event Component

2396	   Component Name: "VEVENT"

2398	   Purpose: Provide a grouping of component properties that describe an
2399	   event.

2401	   Format Definition: A "VEVENT" calendar component is defined by the
2402	   following notation:

2404	     eventc     = "BEGIN" ":" "VEVENT" CRLF
2405	                  eventprop *alarmc
2406	                  "END" ":" "VEVENT" CRLF

2408	     eventprop  = *attach *attendee *categories [class] *comment
2409	                  *contact [created] [description] [dtend / duration]
2410	                  [dtstart] *exdate *exrule [geo] [last-mod] [location]
2411	                  [organizer] [priority] *rstatus *related *resources
2412	                  *rdate *rrule [dtstamp] [seq] [status] [summary]
2413	                  [transp] [uid] [url] [recurid] *x-prop
2414	   Description: A "VEVENT" calendar component is a grouping of component
2415	   properties, and possibly including "VALARM" calendar components, that
2416	   represents a scheduled amount of time on a calendar. For example, it
2417	   can be an activity; such as a one-hour long, department meeting from
2418	   8:00 AM to 9:00 AM, tomorrow. Generally, an event will take up time
2419	   on an individual calendar. Hence, the event will appear as an opaque
2420	   interval in a search for busy time. Alternately, the event can have
2421	   its Time Transparency set to "TRANSPARENT" in order to prevent
2422	   blocking of the event in searches for busy time.

2424	   The "VEVENT" is also the calendar component used to specify an
2425	   anniversary or daily reminder within a calendar. These events have a
2426	   DATE value type for the "DTSTART" property instead of the default
2427	   data type of DATE-TIME. If such a "VEVENT" has a "DTEND" property, it
2428	   MUST be specified as a DATE value also. The anniversary type of
2429	   "VEVENT" can span more than one date (i.e, "DTEND" property value is
2430	   set to a calendar date after the "DTSTART" property value).

2432	   The "DTSTART" property for a "VEVENT" specifies the inclusive start
2433	   of the event. For recurring events, it also specifies the very first
2434	   instance in the recurrence set. The "DTEND" property for a "VEVENT"
2435	   calendar component specifies the non-inclusive end of the event. For
2436	   cases where a "VEVENT" calendar component specifies a "DTSTART"
2437	   property with a DATE data type but no "DTEND" property, the events
2438	   non-inclusive end is the end of the calendar date specified by the
2439	   "DTSTART" property. For cases where a "VEVENT" calendar component
2440	   specifies a "DTSTART" property with a DATE-TIME data type but no
2441	   "DTEND" property, the event ends on the same calendar date and time
2442	   of day specified by the "DTSTART" property.

2444	   The "VEVENT" calendar component cannot be nested within another
2445	   calendar component. However, "VEVENT" calendar components can be
2446	   related to each other or to a "VTODO" or to a "VJOURNAL" calendar
2447	   component with the "RELATED-TO" property.

2449	   Example: The following is an example of the "VEVENT" calendar
2450	   component used to represent a meeting that will also be opaque to
2451	   searches for busy time:

2453	     BEGIN:VEVENT
2454	     UID:19970901T130000Z-123401@host.com
2455	     DTSTAMP:19970901T1300Z
2456	     DTSTART:19970903T163000Z
2457	     DTEND:19970903T190000Z
2458	     SUMMARY:Annual Employee Review
2459	     CLASS:PRIVATE
2460	     CATEGORIES:BUSINESS,HUMAN RESOURCES
2461	     END:VEVENT

2463	   The following is an example of the "VEVENT" calendar component used
2464	   to represent a reminder that will not be opaque, but rather
2465	   transparent, to searches for busy time:

2467	     BEGIN:VEVENT
2468	     UID:19970901T130000Z-123402@host.com
2469	     DTSTAMP:19970901T1300Z
2470	     DTSTART:19970401T163000Z
2471	     DTEND:19970402T010000Z
2472	     SUMMARY:Laurel is in sensitivity awareness class.
2473	     CLASS:PUBLIC
2474	     CATEGORIES:BUSINESS,HUMAN RESOURCES
2475	     TRANSP:TRANSPARENT
2476	     END:VEVENT

2478	   The following is an example of the "VEVENT" calendar component used
2479	   to represent an anniversary that will occur annually. Since it takes
2480	   up no time, it will not appear as opaque in a search for busy time;
2481	   no matter what the value of the "TRANSP" property indicates:

2483	     BEGIN:VEVENT
2484	     UID:19970901T130000Z-123403@host.com
2485	     DTSTAMP:19970901T1300Z
2486	     DTSTART:19971102
2487	     SUMMARY:Our Blissful Anniversary
2488	     CLASS:CONFIDENTIAL
2489	     CATEGORIES:ANNIVERSARY,PERSONAL,SPECIAL OCCASION
2490	     RRULE:FREQ=YEARLY
2491	     END:VEVENT

2493	4.6.2   To-do Component

2495	   Component Name: VTODO

2497	   Purpose: Provide a grouping of calendar properties that describe a
2498	   to-do.

2500	   Formal Definition: A "VTODO" calendar component is defined by the
2501	   following notation:

2503	     todoc      = "BEGIN" ":" "VTODO" CRLF
2504	                  todoprop *alarmc
2505	                  "END" ":" "VTODO" CRLF

2507	     todoprop   = *attach *attendee *categories [class] *comment
2508	                  [completed] *contact [created] [description] [dtstamp]
2509	                  [dtstart] [due / duration] *exdate *exrule [geo]
2510	                  [last-mod] [location] [organizer] [percent] [priority]
2511	                  *rstatus *related *resources *rdate *rrule
2512	                  [recurid] [seq] [status] [summary] [uid] [url]
2513	                  *x-prop

2515	   Description: A "VTODO" calendar component is a grouping of component
2516	   properties and possibly "VALARM" calendar components that represent
2517	   an action-item or assignment. For example, it can be used to
2518	   represent an item of work assigned to an individual; such as "turn in
2519	   travel expense today".

2521	   The "VTODO" calendar component cannot be nested within another
2522	   calendar component. However, "VTODO" calendar components can be
2523	   related to each other or to a "VTODO" or to a "VJOURNAL" calendar
2524	   component with the "RELATED-TO" property.

2526	   A "VTODO" calendar component without the "DTSTART" and "DUE" (or
2527	   "DURATION") properties specifies a to-do that will be associated with
2528	   each successive calendar date, until it is completed.

2530	   Example: The following is an example of a "VTODO" calendar component:

2532	     BEGIN:VTODO
2533	     UID:19970901T130000Z-123404@host.com
2534	     DTSTAMP:19970901T1300Z
2535	     DTSTART:19970415T133000Z
2536	     DUE:19970416T045959Z
2537	     SUMMARY:1996 Income Tax Preparation
2538	     CLASS:CONFIDENTIAL
2539	     CATEGORIES:FAMILY,FINANCE
2540	     PRIORITY:1
2541	     STATUS:NEEDS-ACTION
2542	     END:VEVENT

2544	4.6.3   Journal Component

2546	   Component Name: VJOURNAL

2548	   Purpose: Provide a grouping of component properties that describe a
2549	   journal entry.

2551	   Formal Definition: A "VJOURNAL" calendar component is defined by the
2552	   following notation:

2554	     journalc   = "BEGIN" ":" "VJOURNAL" CRLF
2555	                  jourprop
2556	                  "END" ":" "VJOURNAL" CRLF

2558	     jourprop   = *attach *attendee *categories [class] *comment
2559	                  *contact [created] [description] [dtstart] [dtstamp]
2560	                  *exdate *exrule [last-mod] [organizer] [recurid]
2561	                  *related *rdate *rrule *rstatus [seq] [status]
2562	                  [summary] [uid] [url] *x-prop

2564	   Description: A "VJOURNAL" calendar component is a grouping of
2565	   component properties that represent one or more descriptive text
2566	   notes associated with a particular calendar date. The "DTSTART"
2567	   property is used to specify the calendar date that the journal entry
2568	   is associated with. Generally, it will have a DATE value data type,
2569	   but it can also be used to specify a DATE-TIME value data type.
2570	   Examples of a journal entry include a daily record of a legislative
2571	   body or a journal entry of individual telephone contacts for the day
2572	   or an ordered list of accomplishments for the day. The "VJOURNAL"
2573	   calendar component can also be used to associate a document with a
2574	   calendar date.

2576	   The "VJOURNAL" calendar component does not take up time on a
2577	   calendar. Hence, it does not play a role in free or busy time
2578	   searches - - it is as though it has a time transparency value of
2579	   TRANSPARENT. It is transparent to any such searches.

2581	   The "VJOURNAL" calendar component cannot be nested within another
2582	   calendar component. However, "VJOURNAL" calendar components can be
2583	   related to each other or to a "VEVENT" or to a "VTODO" calendar
2584	   component, with the "RELATED-TO" property.

2586	   Example: The following is an example of the "VJOURNAL" calendar
2587	   component:

2589	     BEGIN:VJOURNAL
2590	     UID:19970901T130000Z-123405@host.com
2591	     DTSTAMP:19970901T1300Z
2592	     DTSTART;VALUE=DATE:19970317
2593	     SUMMARY:Staff meeting minutes
2594	     DESCRIPTION:1. Staff meeting: Participants include Joe\, Lisa
2595	       and Bob. Aurora project plans were reviewed. There is currently
2596	       no budget reserves for this project. Lisa will escalate to
2597	       management. Next meeting on Tuesday.\n
2598	       2. Telephone Conference: ABC Corp. sales representative called
2599	       to discuss new printer. Promised to get us a demo by Friday.\n
2600	       3. Henry Miller (Handsoff Insurance): Car was totaled by tree.
2601	       Is looking into a loaner car. 654-2323 (tel).
2602	     END:VJOURNAL

2604	4.6.4   Free/Busy Component

2606	   Component Name: VFREEBUSY

2608	   Purpose: Provide a grouping of component properties that describe
2609	   either a request for free/busy time, describe a response to a request
2610	   for free/busy time or describe a published set of busy time.

2612	   Formal Definition: A "VFREEBUSY" calendar component is defined by the
2613	   following notation:

2615	     freebusyc  = "BEGIN" ":" "VFREEBUSY" CRLF
2616	                  fbprop
2617	                  "END" ":" "VFREEBUSY" CRLF

2619	     fbprop     = *attendee *comment [contact] [dtstart] [dtend]
2620	                  [duration] [dtstamp] *freebusy [organizer] *rstatus
2621	                  [uid] [url] *x-prop

2623	   Description: A "VFREEBUSY" calendar component is a grouping of
2624	   component properties that represents either a request for, a reply to
2625	   a request for free or busy time information or a published set of
2626	   busy time information.

2628	   When used to request free/busy time information, the "ATTENDEE"
2629	   property specifies the calendar users whose free/busy time is being
2630	   requested; the "ORGANIZER" property specifies the calendar user who
2631	   is requesting the free/busy time; the "DTSTART" and "DTEND"
2632	   properties specify the window of time that the free/busy time is
2633	   being requested; the "UID" and "DTSTAMP" properties are specified to
2634	   assist in proper sequencing of multiple free/busy time requests.

2636	   When used to reply to a request for free/busy time, the "ATTENDEE"
2637	   property specifies the calendar user responding to the free/busy time
2638	   request; the "ORGANIZER" property specifies the calendar user that
2639	   originally requested the free/busy time; the "FREEBUSY" property
2640	   specifies the free/busy time information; and the "UID" and "DTSTAMP"
2641	   properties are specified to assist in proper sequencing of multiple
2642	   free/busy time replies.

2644	   When used to publish busy time, the "ORGANIZER" property specifies
2645	   the calendar user associated with the published busy time; the
2646	   "DTSTART" and "DTEND" properties specify an inclusive time window
2647	   that surrounds the busy time information; the "FREEBUSY" property
2648	   specifies the published busy time information; and the "DTSTAMP"
2649	   property specifies the date/time that iCalendar object was created.

2651	   The "VFREEBUSY" calendar component cannot be nested within another
2652	   calendar component. Multiple "VFREEBUSY" calendar components can be
2653	   specified within an iCalendar object. This permits the grouping of
2654	   Free/Busy information into logical collections, such as monthly
2655	   groups of busy time information.

2657	   The "VFREEBUSY" calendar component is intended for use in iCalendar
2658	   object methods involving requests for free time, requests for busy
2659	   time, requests for both free and busy, and the associated replies.

2661	   Free/Busy information is represented with the "FREEBBUSY" property.
2662	   This property provides a terse representation of time periods. One or
2663	   more "FREEBUSY" properties can be specified in the "VFREEBUSY"
2664	   calendar component.

2666	   When present in a "VFREEBUSY" calendar component, the "DTSTART" and
2667	   "DTEND" properties SHOULD be specified prior to any "FREEBUSY"
2668	   properties. In a free time request, these properties can be used in
2669	   combination with the "DURATION" property to represent a request for a
2670	   duration of free time within a specified window of time.

2672	   The recurrence properties ("RRULE", "EXRULE", "RDATE", "EXDATE") are
2673	   not permitted within a "VFREEBUSY" calendar component. Any recurring
2674	   events are resolved into their individual busy time periods using the
2675	   "FREEBUSY" property.

2677	   Example: The following is an example of a "VFREEBUSY" calendar
2678	   component used to request free or busy time information:

2680	     BEGIN:VFREEBUSY
2681	     ORGANIZER:MAILTO:jane_doe@host1.com
2682	     ATTENDEE:MAILTO:john_public@host2.com
2683	     DTSTART:19971015T050000Z
2684	     DTEND:19971016T050000Z
2685	     DTSTAMP:19970901T083000Z
2686	     END:VFREEBUSY

2688	   The following is an example of a "VFREEBUSY" calendar component used
2689	   to reply to the request with busy time information:

2691	     BEGIN:VFREEBUSY
2692	     ORGANIZER:MAILTO:jane_doe@host1.com
2693	     ATTENDEE:MAILTO:john_public@host2.com
2694	     DTSTAMP:19970901T100000Z
2695	     FREEBUSY;VALUE=PERIOD:19971015T050000Z/PT8H30M,
2696	      19971015T160000Z/PT5H30M,19971015T223000Z/PT6H30M
2697	     URL:http://host2.com/pub/busy/jpublic-01.ifb
2698	     COMMENT:This iCalendar file contains busy time information for
2699	       the next three months.
2700	     END:VFREEBUSY

2702	   The following is an example of a "VFREEBUSY" calendar component used
2703	   to published busy time information.

2705	     BEGIN:VFREEBUSY
2706	     ORGANIZER:jsmith@host.com
2707	     DTSTART:19980313T141711Z
2708	     DTEND:19980410T141711Z
2709	     FREEBUSY:19980314T233000Z/19980315T003000Z
2710	     FREEBUSY:19980316T153000Z/19980316T163000Z
2711	     FREEBUSY:19980318T030000Z/19980318T040000Z
2712	     URL:http://www.host.com/calendar/busytime/jsmith.ifb
2713	     END:VFREEBUSY

2715	4.6.5   Time Zone Component

2717	   Component Name: VTIMEZONE

2719	   Purpose: Provide a grouping of component properties that defines a
2720	   time zone.

2722	   Formal Definition: A "VTIMEZONE" calendar component is defined by the
2723	   following notation:

2725	     timezonec  = "BEGIN" ":" "VTIMEZONE" CRLF

2727	                  tzid [last-mod] [tzurl] 1*(standardc / daylightc)
2728	                  *x-prop

2730	                  "END" ":" "VTIMEZONE" CRLF

2732	     standardc  = "BEGIN" ":" "STANDARD" CRLF

2734	                  tzprop

2736	                  "END" ":" "STANDARD" CRLF
2737	     daylightc  = "BEGIN" ":" "DAYLIGHT" CRLF

2739	                  tzprop

2741	                  "END" ":" "DAYLIGHT" CRLF

2743	     tzprop     = *comment dtstart (*rdate / *rrule)
2744	                  *tzname tzoffsetto tzoffsetfrom *x-prop

2746	   Description: A time zone is unambiguously defined by the set of time
2747	   measurement rules determined by the governing body for a given
2748	   geographic area. These rules describe at a minimum the base  offset
2749	   from UTC for the time zone, often referred to as the Standard Time
2750	   offset. Many locations adjust their Standard Time forward or backward
2751	   by one hour, in order to accommodate seasonal changes in number of
2752	   daylight hours, often referred to as Daylight  Saving Time. Some
2753	   locations adjust their time by a fraction of an hour. Standard Time
2754	   is also known as Winter Time. Daylight Saving Time is also known as
2755	   Advanced Time, Summer Time, or Legal Time in certain countries. The
2756	   following table shows the changes in time zone rules for the eastern
2757	   United States starting from 1967. Each line represents a description
2758	   or rule for a particular observance.

2760	     Effective Observance Rule

2762	     Date       (Date/Time)             Offset  Abbreviation

2764	     1967-*     lastSun in Oct, 02:00   -0500   EST

2766	     1967-1973  last Sun in Apr, 02:00  -0400   EDT

2768	     1974-1974  Jan 6,  02:00           -0400   EDT

2770	     1975-1975  Feb 23, 02:00           -0400   EDT

2772	     1976-1986  last Sun in Apr, 02:00  -0400   EDT

2774	     1987-*     first Sun in Apr, 02:00 -0400   EDT

2776	   Interoperability between two calendaring and scheduling applications,
2777	   especially for  recurring events, to-dos or journal entries, is
2778	   dependent on the ability to capture and  convey date and time
2779	   information in an unambiguous format. The specification of current
2780	   time  zone information is integral to this behavior.

2782	   If present, the "VTIMEZONE" calendar component defines the set of
2783	   Standard Time and Daylight Saving Time observances (or rules) for a
2784	   particular time zone for a given interval of time. The "VTIMEZONE"
2785	   calendar component cannot be nested within other calendar components.
2786	   Multiple "VTIMEZONE" calendar components can exist in an iCalendar
2787	   object. In this situation, each "VTIMEZONE" MUST represent a unique
2788	   time zone definition. This is necessary for some classes of events,
2789	   such as airline flights, that start in one time zone and end in
2790	   another.

2792	   The "VTIMEZONE" calendar component MUST be present if the iCalendar
2793	   object contains an RRULE that generates dates on both sides of a time
2794	   zone shift (e.g. both in Standard Time and Daylight Saving Time)
2795	   unless the iCalendar object intends to convey a floating time (See
2796	   the section "4.1.10.11 Time" for proper interpretation of floating
2797	   time). It can be present if the iCalendar object does not contain
2798	   such a RRULE. In addition, if a RRULE is present, there must be valid
2799	   time zone information for all recurrence instances.

2801	   The "VTIMEZONE" calendar component MUST include the "TZID" property
2802	   and at least one definition of a standard or daylight component. The
2803	   standard or daylight component MUST include the "DTSTART",
2804	   "TZOFFSETFROM" and "TZOFFSETTO" properties.

2806	   An individual "VTIMEZONE" calendar component MUST be specified for
2807	   each unique "TZID" parameter value specified in the iCalendar object.

2809	   Each "VTIMEZONE" calendar component consists of a collection of one
2810	   or more sub-components that describe the rule for a particular
2811	   observance (either a Standard Time or a Daylight Saving Time
2812	   observance). The "STANDARD" sub-component consists of a collection of
2813	   properties that describe Standard Time. The "DAYLIGHT" sub-component
2814	   consists of a collection of properties that describe Daylight Saving
2815	   Time. In general this collection of properties consists of:

2817	        - the first onset date-time for the observance

2819	        - the last onset date-time for the observance, if a last onset
2820	        is known.

2822	        - the offset to be applied for the observance

2824	        - a rule that describes the day and time when the observance
2825	        takes effect

2827	        - an optional name for the observance

2829	   For a given time zone, there may be multiple unique definitions of
2830	   the observances over a period of time. Each observance is described
2831	   using either a "STANDARD" or "DAYLIGHT" sub-component. The collection
2832	   of these sub-components is used to describe the time zone for a given
2833	   period of time. The offset to apply at any given time is found by
2834	   locating the observance that has the last onset date and time before
2835	   the time in question, and using the offset value from that
2836	   observance.

2838	   The top-level properties in a "VTIMEZONE" calendar component are:

2840	   The mandatory "TZID" property is a text value that uniquely
2841	   identifies the VTIMZONE calendar component within the scope of an
2842	   iCalendar object.

2844	   The optional "LAST-MODIFIED" property is a UTC value that specifies
2845	   the date and time that this time zone definition was last updated.

2847	   The optional "TZURL" property is url value that points to a published
2848	   VTIMEZONE definition.

2850	   The collection of properties that are used to define the STANDARD and
2851	   DAYLIGHT sub-components include:

2853	   The mandatory "DTSTART" property gives the effective onset date and
2854	   local time for the time zone sub-component definition. "DTSTART" in
2855	   this usage MUST be specified as a local DATE-TIME value.

2857	   The mandatory "TZOFFSETFROM" property gives the UTC offset which is
2858	   in use when the onset of this time zone observance begins.
2859	   "TZOFFSETFROM" is combined with "DTSTART" to define the effective
2860	   onset for the time zone sub-component definition. For  example, the
2861	   following represents the time at which the observance of Standard
2862	   Time took effect in Fall 1967 for the eastern United States:

2864	     DTSTART:19671029T020000

2866	     TZOFFSETFROM:-0400

2868	   The mandatory "TZOFFSETTO " property gives the UTC offset for the
2869	   time zone sub-component (Standard Time or Daylight Saving Time) when
2870	   this observance is in use.

2872	   The optional "TZNAME" property is the customary name for the time
2873	   zone. It may be specified multiple times, to allow for specifying
2874	   multiple language variants of the time zone names. This could be used
2875	   for displaying dates.

2877	   If specified, the onset for the observance defined by the time zone
2878	   sub-component is defined by either the "RRULE" or "RDATE" property.
2879	   If neither are specified, only one sub-component can be specified in
2880	   the "VTIMEZONE" calendar component and it is assumed that the single
2881	   observance specified is always in effect.

2883	   The "RRULE" property defines the recurrence rule for the onset of the
2884	   observance defined by this time zone sub-component. Some specific
2885	   requirements for the usage of RRULE for this purpose include:

2887	        - If observance is known to have an effective end date, the
2888	        "UNTIL" recurrence rule parameter MUST be used to specify the
2889	        last valid onset of this observance (i.e., the UNTIL date-time
2890	        will be equal to the last instance generated by the recurrence
2891	        pattern). It MUST be specified in UTC time.

2893	        - The "DTSTART" and the "TZOFFSETTO" properties MUST be used
2894	        when generating the onset date-time values (instances) from the
2895	        RRULE.

2897	   Alternatively, the "RDATE" property can be used to define the onset
2898	   of the observance by giving the individual onset date and times.
2899	   "RDATE" in this usage MUST be specified as a local DATE-TIME value in
2900	   UTC time.

2902	   The optional "COMMENT" property is also allowed for descriptive
2903	   explanatory text.

2905	   Example: The following are examples of the "VTIMEZONE" calendar
2906	   component:

2908	   This is an example showing time zone information for the Eastern
2909	   United States using "RDATE" property. Note that this is only suitable
2910	   for a recurring event that starts on or later than April 6, 1997 at
2911	   03:00:00 EDT (i.e., the earliest effective transition date and  time)
2912	   and ends no later than April 7, 1998 02:00:00 EST (i.e., latest valid
2913	   date and time for EST in this scenario). For example, this can be
2914	   used for a recurring event that occurs every Friday, 8am-9:00 AM,
2915	   starting June 1, 1997, ending December 31, 1997.

2917	     BEGIN:VTIMEZONE
2918	     TZID:America-New_York
2919	     LAST-MODIFIED:19870101T000000Z
2920	     BEGIN:STANDARD
2921	     DTSTART:19971026T020000
2922	     RDATE:19971026T020000
2923	     TZOFFSETFROM:-0400
2924	     TZOFFSETTO:-0500
2925	     TZNAME:EST
2926	     END:STANDARD
2927	     BEGIN:DAYLIGHT
2928	     DTSTART:19971026T020000
2929	     RDATE:19970406T020000
2930	     TZOFFSETFROM:-0500
2931	     TZOFFSETTO:-0400
2932	     TZNAME:EDT
2933	     END:DAYLIGHT
2934	     END:VTIMEZONE

2936	   This is a simple example showing the current time zone rules for the
2937	   Eastern United States using a RRULE recurrence pattern. Note that
2938	   there is no effective end date to either of the Standard Time or
2939	   Daylight Time rules. This information would be valid for a recurring
2940	   event starting today and continuing on into the known future.

2942	     BEGIN:VTIMEZONE
2943	     TZID:America-New_York
2944	     LAST-MODIFIED:19870101T000000Z
2945	     TZURL:http://zones.stds_r_us.net/tz/America-New_York
2946	     BEGIN:STANDARD
2947	     DTSTART:19671029T020000
2948	     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
2949	     TZOFFSETFROM:-0400
2950	     TZOFFSETTO:-0500
2951	     TZNAME:EST
2952	     END:STANDARD
2953	     BEGIN:DAYLIGHT
2954	     DTSTART:19870405T020000
2955	     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4
2956	     TZOFFSETFROM:-0500
2957	     TZOFFSETTO:-0400
2958	     TZNAME:EDT
2959	     END:DAYLIGHT
2960	     END:VTIMEZONE

2962	   This is an example showing a fictitious set of rules for the Eastern
2963	   United States, where the Daylight Time rule has an effective end date
2964	   (i.e., after that date, Daylight Time is no longer observed).

2966	     BEGIN:VTIMEZONE
2967	     TZID:America-New_York
2968	     LAST-MODIFIED:19870101T000000Z
2969	     BEGIN:STANDARD
2970	     DTSTART:19671029T020000
2971	     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
2972	     TZOFFSETFROM:-0400
2973	     TZOFFSETTO:-0500
2974	     TZNAME:EST
2975	     END:STANDARD
2976	     BEGIN:DAYLIGHT
2977	     DTSTART:19870405T020000
2978	     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z
2979	     TZOFFSETFROM:-0500
2980	     TZOFFSETTO:-0400
2981	     TZNAME:EDT
2982	     END:DAYLIGHT
2983	     END:VTIMEZONE

2985	   This is an example showing a fictitious set of rules for the Eastern
2986	   United States, where  the first Daylight Time rule has an effective
2987	   end date. There is a second Daylight Time rule that picks up where
2988	   the other left off.

2990	     BEGIN:VTIMEZONE
2991	     TZID:America-New_York
2992	     LAST-MODIFIED:19870101T000000Z
2993	     BEGIN:STANDARD
2994	     DTSTART:19671029T020000
2995	     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
2996	     TZOFFSETFROM:-0400
2997	     TZOFFSETTO:-0500
2998	     TZNAME:EST
2999	     END:STANDARD
3000	     BEGIN:DAYLIGHT
3001	     DTSTART:19870405T020000
3002	     RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=4;UNTIL=19980404T070000Z
3003	     TZOFFSETFROM:-0500
3004	     TZOFFSETTO:-0400
3005	     TZNAME:EDT
3006	     END:DAYLIGHT
3007	     BEGIN:DAYLIGHT
3008	     DTSTART:19990424T020000
3009	     RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=4
3010	     TZOFFSETFROM:-0500
3011	     TZOFFSETTO:-0400
3012	     TZNAME:EDT
3013	     END:DAYLIGHT
3014	     END:VTIMEZONE

3016	4.6.6   Alarm Component

3018	   Component Name: VALARM

3020	   Purpose: Provide a grouping of component properties that define an
3021	   alarm.

3023	   Formal Definition: A "VALARM" calendar component is defined by the
3024	   following notation:

3026	     alarmc     = "BEGIN" ":" "VALARM" CRLF
3027	                  (audioprop / dispprop / emailprop / procprop)
3028	                  "END" ":" "VALARM" CRLF

3030	     audioprop  = action trigger [duration repeat] [attach] *x-prop

3032	     dispprop   = action description trigger [duration
3033	                  repeat] *x-prop

3035	     emailprop  = action 1*attendee *attach description
3036	                  trigger [duration repeat] summary *x-prop

3038	     procprop   = action attach [description] trigger [duration
3039	                  repeat] *x-prop

3041	   Description: A "VALARM" calendar component is a grouping of component
3042	   properties that is a reminder or alarm for an event or a to-do. For
3043	   example, it may be used to define a reminder for a pending event or
3044	   an overdue to-do.

3046	   The "VALARM" calendar component MUST include the "ACTION" and
3047	   "TRIGGER" properties. The "ACTION" property further constrains the
3048	   "VALARM" calendar component in the following ways:

3050	   When the action is "AUDIO", the alarm can also include one and only
3051	   one "ATTACH" property, which MUST point to a sound resource, which is
3052	   rendered when the alarm is triggered.

3054	   When the action is "DISPLAY", the alarm MUST also include a
3055	   "DESCRIPTION" property, which contains the text to be displayed when
3056	   the alarm is triggered.

3058	   When the action is "EMAIL", the alarm MUST include a "DESCRIPTION"
3059	   property, which contains the text to be used as the message body, a
3060	   "SUMMARY" property, which contains the text to be used as the message
3061	   subject, and one or more "ATTENDEE" properties, which contain the
3062	   email address of attendees to receive the message. It can also
3063	   include one or more "ATTACH" properties, which are intended to be
3064	   sent as message attachments. When the alarm is triggered, the email
3065	   message is sent.

3067	   When the action is "PROCEDURE", the alarm MUST include one and only
3068	   one "ATTACH" property, which MUST point to a procedure resource,
3069	   which is invoked when the alarm is triggered.

3071	   The "VALARM" calendar component MUST only appear within either a
3072	   "VEVENT" or "VTODO" calendar component. "VALARM" calendar components
3073	   cannot be nested. Multiple mutually independent "VALARM" calendar
3074	   components can be specified for a single "VEVENT" or "VTODO" calendar
3075	   component.

3077	   The "TRIGGER" property specifies when the alarm will be triggered.
3078	   The "TRIGGER" property specifies a duration prior to the start of an
3079	   event or a to-do. The "TRIGGER" edge may be explicitly set to be
3080	   relative to the "START" or "END" of the event or to-do with the
3081	   "RELATED" parameter of the "TRIGGER" property. The "TRIGGER" property
3082	   value type can alternatively be set to an absolute calendar date and
3083	   time of day value.

3085	   In an alarm set to trigger on the "START" of an event or to-do, the
3086	   "DTSTART" property MUST be present in the associated event or to-do.
3087	   In an alarm in a "VEVENT" calendar component set to trigger on the
3088	   "END" of the event, either the "DTEND" property MUST be present, or
3089	   the "DTSTART" and "DURATION" properties MUST both be present. In an
3090	   alarm in a "VTODO" calendar component set to trigger on the "END" of
3091	   the to-do, either the "DUE" property MUST be present, or the
3092	   "DTSTART" and "DURATION" properties MUST both be present.

3094	   The alarm can be defined such that it triggers repeatedly. A
3095	   definition of an alarm with a repeating trigger MUST include both the
3096	   "DURATION" and "REPEAT" properties. The "DURATION" property specifies
3097	   the delay period, after which the alarm will repeat. The "REPEAT"
3098	   property specifies the number of additional repetitions that the
3099	   alarm will triggered. This repitition count is in addition to the
3100	   initial triggering of the alarm. Both of these properties must be
3101	   present in order to specify a repeating alarm. If one of these two
3102	   properties is absent, then the alarm will not repeat beyond the
3103	   initial trigger.

3105	   The "ACTION" property is used within the "VALARM" calendar component
3106	   to specify the type of action invoked when the alarm is triggered.
3107	   The "VALARM" properties provide enough information for a specific
3108	   action to be invoked. It is typically the responsibility of a
3109	   "Calendar User Agent" (CUA) to deliver the alarm in the specified
3110	   fashion. An "ACTION" property value of AUDIO specifies an alarm that
3111	   causes a sound to be played to alert the user; DISPLAY specifies an
3112	   alarm that causes a text message to be displayed to the user; EMAIL
3113	   specifies an alarm that causes an electronic email message to be
3114	   delivered to one or more email addresses; and PROCEDURE specifies an
3115	   alarm that causes a procedure to be executed. The "ACTION" property
3116	   MUST specify one and only one of these values.

3118	   In an AUDIO alarm, if the optional "ATTACH" property is included, it
3119	   MUST specify an audio sound resource. The intention is that the sound
3120	   will be played as the alarm effect. If an "ATTACH" property is
3121	   specified that does not refer to a sound resource, or if the
3122	   specified sound resource cannot be rendered (because its format is
3123	   unsupported, or because it cannot be retrieved), then the CUA or
3124	   other entity responsible for playing the sound may choose a fallback
3125	   action, such as playing a built-in default sound, or playing no sound
3126	   at all.

3128	   In a DISPLAY alarm, the intended alarm effect is for the text value
3129	   of the "DESCRIPTION" property to be displayed to the user.

3131	   In an EMAIL alarm, the intended alarm effect is for an email message
3132	   to be composed and delivered to all the addresses specified by the
3133	   "ATTENDEE" properties in the "VALARM" calendar component. The
3134	   "DESCRIPTION" property of the "VALARM" calendar component MUST be
3135	   used as the body text of the message, and the "SUMMARY" property MUST
3136	   be used as the subject text. Any "ATTACH" properties in the "VALARM"
3137	   calendar component SHOULD be sent as attachments to the message.

3139	   In a PROCEDURE alarm, the "ATTACH" property in the "VALARM" calendar
3140	   component MUST specify a procedure or program that is intended to be
3141	   invoked as the alarm effect. If the procedure or program is in a
3142	   format that cannot be rendered, then no procedure alarm will be
3143	   invoked. If the "DESCRIPTION" property is present, its value
3144	   specifies the argument string to be passed to the procedure or
3145	   program. "Calendar User Agents" that receive an iCalendar object with
3146	   this category of alarm, can disable or allow the "Calendar User" to
3147	   disable, or otherwise ignore this type of alarm. While a very useful
3148	   alarm capability, the PROCEDURE type of alarm should be treated by
3149	   the "Calendar User Agent" as a potential security risk.

3151	   Example: The following example is for a "VALARM" calendar component
3152	   that specifies an audio alarm that will sound at a precise time and
3153	   repeat 4 more times at 15 minute intervals:

3155	     BEGIN:VALARM
3156	     TRIGGER;VALUE=DATE-TIME:19970317T133000Z
3157	     REPEAT:4
3158	     DURATION:PT15M
3159	     ACTION:AUDIO
3160	     ATTACH:ftp://host.com/pub/sounds/bell-01.wav
3161	     END:VALARM

3163	   The following example is for a "VALARM" calendar component that
3164	   specifies a display alarm that will trigger 30 minutes before the
3165	   scheduled start of the event or the due date/time of the to-do it is
3166	   associated with and will repeat 2 more times at 15 minute intervals:

3168	     BEGIN:VALARM
3169	     TRIGGER:PT30M
3170	     REPEAT:2
3171	     DURATION:PT15M
3172	     ACTION:DISPLAY
3173	     DESCRIPTION:Breakfast meeting with executive\n
3174	      team at 8:30 AM EST.
3175	     END:VALARM

3177	   The following example is for a "VALARM" calendar component that
3178	   specifies an email alarm that will trigger 2 days before the
3179	   scheduled due date/time of a to-do it is associated with. It does not
3180	   repeat. The email has a subject, body and attachment link.

3182	     BEGIN:VALARM
3183	     TRIGGER:P2D
3184	     ACTION:EMAIL
3185	     ATTENDEE:MAILTO:john_doe@host.com
3186	     SUMMARY:*** REMINDER: SEND AGENDA FOR WEEKLY STAFF MEETING ***
3187	     DESCRIPTION:A draft agenda needs to be sent out to the attendees
3188	       to the weekly managers meeting (MGR-LIST). Attached is a
3189	       pointer the document template for the agenda file.
3190	     ATTACH:http://host.com/templates/agenda.doc
3191	     END:VALARM

3193	   The following example is for a "VALARM" calendar component that
3194	   specifies a procedural alarm that will trigger at a precise date/time
3195	   and will repeat 23 more times at one hour intervals. The alarm will
3196	   invoke a procedure file.

3198	     BEGIN:VALARM
3199	     TRIGGER;VALUE=DATE-TIME:19980101T050000Z
3200	     REPEAT:23
3201	     DURATION:PT1H
3202	     ACTION:PROCEDURE
3203	     ATTACH:ftp://host.com/novo-procs/felizano.exe
3204	     END:VALARM

3206	4.7 Calendar Properties

3208	   The Calendar Properties are attributes that apply to the iCalendar
3209	   object, as a whole. These properties do not appear within a calendar
3210	   component. They should be specified after the "BEGIN:VCALENDAR"
3211	   property and prior to any calendar component.

3213	4.7.1   Calendar Scale

3215	   Property Name: CALSCALE

3217	   Purpose: This property defines the calendar scale used for the
3218	   calendar information specified in the iCalendar object.

3220	   Value Type: TEXT

3222	   Property Parameters: Non-standard property parameters can be
3223	   specified on this property.

3225	   Conformance: Property can be specified in an iCalendar object. The
3226	   default value is "GREGORIAN".

3228	   Description: This memo is based on the Gregorian calendar scale. The
3229	   Gregorian calendar scale is assumed if this property is not specified
3230	   in the iCalendar object. It is expected that other calendar scales
3231	   will be defined in other specifications or by future versions of this
3232	   memo.

3234	   Format Definition: The property is defined by the following notation:

3236	     calscale   = "CALSCALE" calparam ":" calvalue CRLF

3238	     calparam   = *(";" xparam)

3240	     calvalue   = "GREGORIAN" / iana-token

3242	   Example: The following is an example of this property:

3244	     CALSCALE:GREGORIAN

3246	4.7.2   Method

3248	   Property Name: METHOD

3250	   Purpose: This property defines the iCalendar object method associated
3251	   with the calendar object.

3253	   Value Type: TEXT

3255	   Property Parameters: Non-standard property parameters can be
3256	   specified on this property.

3258	   Conformance: The property can be specified in an iCalendar object.

3260	   Description: When used in a MIME message entity, the value of this
3261	   property MUST be the same as the Content-Type "method" parameter
3262	   value. This property can only appear once within the iCalendar
3263	   object. If either the "METHOD" property or the Content-Type "method"
3264	   parameter is specified, then the other must also be specified.

3266	   No methods are defined by this specification. This is the subject of
3267	   other specifications, such as the iCalendar Transport-independent
3268	   Interoperability Protocol (iTIP) defined by [ITIP].

3270	   If this property is not present in the iCalendar object, then a
3271	   scheduling transaction MUST NOT be assumed. In such cases, the
3272	   iCalendar object is merely being used to transport a snapshot of some
3273	   calendar information; without the intention of conveying a scheduling
3274	   semantic.

3276	   Format Definition: The property is defined by the following notation:

3278	     method     = "METHOD" metparam ":" metvalue CRLF
3279	     metparam   = *(";" xparam)

3281	     metvalue   = iana-token

3283	   Example: The following is a hypothetical example of this property to
3284	   convey that the iCalendar object is a request for a meeting:

3286	     METHOD:REQUEST

3288	4.7.3   Product Identifier

3290	   Property Name: PRODID

3292	   Purpose: This property specifies the identifier for the product that
3293	   created the iCalendar object.

3295	   Value Type: TEXT

3297	   Property Parameters: Non-standard property parameters can be
3298	   specified on this property.

3300	   Conformance: The property MUST be specified once in an iCalendar
3301	   object.

3303	   Description: The vendor of the implementation should assure that this
3304	   is a globally unique identifier; using some technique such as an FPI
3305	   value, as defined in [ISO 9070].

3307	   This property should not be used to alter the interpretation of an
3308	   iCalendar object beyond the semantics specified in this memo. For
3309	   example, it is not to be used to further the understanding of non-
3310	   standard properties.

3312	   Format Definition: The property is defined by the following notation:

3314	     prodid     = "PRODID" pidparam ":" pidvalue CRLF

3316	     pidparam   = *(";" xparam)

3318	     pidvalue   = text
3319	     ;Any text that describes the product and version
3320	     ;and that is generally assured of being unique.

3322	   Example: The following is an example of this property. It does not
3323	   imply that English is the default language.

3325	     PRODID:-//ABC Corporation//NONSGML My Product//EN

3327	4.7.4   Version

3329	   Property Name: VERSION

3331	   Purpose: This property specifies the identifier corresponding to the
3332	   highest version number or the minimum and maximum range of the
3333	   iCalendar specification that is required in order to interpret the
3334	   iCalendar object.

3336	   Value Type: TEXT

3338	   Property Parameters: Non-standard property parameters can be
3339	   specified on this property.

3341	   Conformance: This property MUST be specified by an iCalendar object,
3342	   but MUST only be specified once.

3344	   Description: A value of "2.0" corresponds to this memo.

3346	   Format Definition: The property is defined by the following notation:

3348	     version    = "VERSION" verparam ":" vervalue CRLF

3350	     verparam   = *(";" xparam)

3352	     vervalue   = "2.0"         ;This memo
3353	                / maxver
3354	                / (minver ";" maxver)

3356	     minver     = <A IANA registered iCalendar version identifier>
3357	     ;Minimum iCalendar version needed to parse the iCalendar object

3359	     maxver     = <A IANA registered iCalendar version identifier>
3360	     ;Maximum iCalendar version needed to parse the iCalendar object

3362	   Example: The following is an example of this property:

3364	     VERSION:2.0

3366	4.8 Component Properties

3368	   The following properties can appear within calendar components, as
3369	   specified by each component property definition.

3371	4.8.1   Descriptive Component Properties

3373	   The following properties specify descriptive information about
3374	   calendar components.

3376	4.8.1.1 Attachment

3378	   Property Name: ATTACH

3380	   Purpose: The property provides the capability to associate a document
3381	   object with a calendar component.

3383	   Value Type: The default value type for this property is URI. The
3384	   value type can also be reset to BINARY in order to include inline
3385	   binary encoded content information.

3387	   Property Parameters: Non-standard, inline encoding, value data type
3388	   property parameters can be specified on this property.

3390	   Conformance: The property can be specified in an iCalendar object.

3392	   Description: The property can be specified within "VEVENT", "VTODO",
3393	   "VJOURNAL", or "VALARM" calendar components. This property can be
3394	   specified multiple times within an iCalendar object.

3396	   Format Definition: The property is defined by the following notation:

3398	     attach     = "ATTACH" attparam ":" uri  CRLF

3400	     attach     =/ "ATTACH" attparam ";" "ENCODING" "=" "BASE64"
3401	                   ";" "VALUE" "=" "BINARY" ":" binary

3403	     attparam   = *(";" xparam)

3405	   Example: The following are examples of this property:

3407	     ATTACH:CID:jsmith.part3.960817T083000.xyzMail@host1.com

3409	     ATTACH:FTP://xyzCorp.com/pub/reports/r-960812.ps

3411	4.8.1.2 Categories

3413	   Property Name: CATEGORIES

3415	   Purpose: This property defines the categories for a calendar
3416	   component.

3418	   Value Type: TEXT

3420	   Property Parameters: Non-standard and language property parameters
3421	   can be specified on this property.

3423	   Conformance: The property can be specified within "VEVENT", "VTODO"
3424	   or "VJOURNAL" calendar components.

3426	   Description: This property is used to specify categories or subtypes
3427	   of the calendar component. The categories are useful in searching for
3428	   a calendar component of a particular type and category. Within the
3429	   "VEVENT", "VTODO" or "VJOURNAL" calendar components, more than one
3430	   category can be specified as a list of categories separated by the
3431	   COMMA character (US-ASCII decimal 44).

3433	   Format Definition: The property is defined by the following notation:

3435	     categories = "CATEGORIES" catparam ":" text *("," text)
3436	                  CRLF

3438	     catparam   = [";" languageparam]
3439	                  *(";" xparam)
3440	   Example: The following are examples of this property:

3442	     CATEGORIES:APPOINTMENT,EDUCATION

3444	     CATEGORIES:MEETING

3446	4.8.1.3 Classification

3448	   Property Name: CLASS

3450	   Purpose: This property defines the access classification for a
3451	   calendar component.

3453	   Value Type: TEXT

3455	   Property Parameters: Non-standard property parameters can be
3456	   specified on this property.

3458	   Conformance: The property can be specified once in a "VEVENT",
3459	   "VTODO" or "VJOURNAL" calendar components.

3461	   Description: An access classification is only one component of the
3462	   general security system within a calendar application. It provides a
3463	   method of capturing the scope of the access the calendar owner
3464	   intends for information within an individual calendar entry. The
3465	   access classification of an individual iCalendar component is useful
3466	   when measured along with the other security components of a calendar
3467	   system (e.g., calendar user authentication, authorization, access
3468	   rights, access role, etc.). Hence, the semantics of the individual
3469	   access classifications cannot be completely defined by this memo
3470	   alone. Additionally, due to the "blind" nature of most exchange
3471	   processes using this memo, these access classifications cannot serve
3472	   as an enforcement statement for a system receiving an iCalendar
3473	   object. Rather, they provide a method for capturing the intention of
3474	   the calendar owner for the access to the calendar component. The
3475	   [ICMS] provides a broader description of the security system within a
3476	   calendar application.

3478	   Format Definition: The property is defined by the following notation:

3480	     class      = "CLASS" classparam ":" classvalue CRLF

3482	     classparam = *(";" xparam)

3484	     classvalue = "PUBLIC" / "PRIVATE" / "CONFIDENTIAL" / iana-token
3485	                / x-name
3486	     ;Default is PUBLIC

3488	   Example: The following is an example of this property:

3490	     CLASS:PUBLIC
3491	4.8.1.4 Comment

3493	   Property Name: COMMENT

3495	   Purpose: This property specifies non-processing information intended
3496	   to provide a comment to the calendar user.

3498	   Value Type: TEXT

3500	   Property Parameters: Non-standard, alternate text representation and
3501	   language property parameters can be specified on this property.

3503	   Conformance: This property can be specified in an iCalendar object.

3505	   Description: The property can be specified multiple times.

3507	   Format Definition: The property is defined by the following notation:

3509	     comment    = "COMMENT" commparam ":" text CRLF

3511	     commparam  = [";" altrepparam ] [";" languageparam]
3512	                  *(";" xparam)

3514	   Example: The following is an example of this property:

3516	     COMMENT:The meeting really needs to include both ourselves
3517	       and the customer. We can't hold this  meeting without them.
3518	       As a matter of fact\, the venue for the meeting ought to be at
3519	       their site. - - John

3521	   The data type for this property is TEXT.

3523	4.8.1.5 Description

3525	   Property Name: DESCRIPTION

3527	   Purpose: This property provides a more complete description of the
3528	   calendar component, than that provided by the "SUMMARY" property.

3530	   Value Type: TEXT

3532	   Property Parameters: Non-standard, alternate text representation and
3533	   language property parameters can be specified on this property.

3535	   Conformance: The property can be specified in the "VEVENT", "VTODO",
3536	   "VJOURNAL" and "VALARM" calendar components. The property can be
3537	   specified multiple times only within a "VJOURNAL" calendar component.

3539	   Description: This property is used in the "VEVENT" and "VTODO" to
3540	   capture lengthy textual decriptions associated with the activity.

3542	   This property is used in the "VJOURNAL" calendar component to capture
3543	   one more textual journal entries.

3545	   This property is used in the "VALARM" calendar component to capture
3546	   the display text for a DISPLAY category of alarm, to capture the body
3547	   text for an EMAIL category of alarm and to capture the arguement
3548	   string for a PROCEDURE category of alarm.

3550	   Format Definition: The property is defined by the following notation:

3552	     description        = "DESCRIPTION" descparam ":" text CRLF

3554	     descparam  = [";" altrepparam] [";" languageparam]
3555	                  *(";" xparam)

3557	   Example: The following is an example of the property with formatted
3558	   line breaks in the property value:

3560	     DESCRIPTION:Meeting to provide technical review for "Phoenix"
3561	       design.\n Happy Face Conference Room. Phoenix design team
3562	       MUST attend this meeting.\n RSVP to team leader.

3564	   The following is an example of the property with folding of long
3565	   lines:

3567	     DESCRIPTION:Last draft of the new novel is to be completed
3568	       for the editor's proof today.

3570	4.8.1.6 Geographic Position

3572	   Property Name: GEO

3574	   Purpose: This property specifies information related to the global
3575	   position for the activity specified by a calendar component.

3577	   Value Type: FLOAT. The value MUST be two SEMICOLON separated FLOAT
3578	   values.

3580	   Property Parameters: Non-standard property parameters can be
3581	   specified on this property.

3583	   Conformance: This property can be specified in an iCalendar object.

3585	   Description: The property value specifies latitude and longitude, in
3586	   that order (i.e., "LAT LON" ordering). The longitude represents the
3587	   location east and west of the prime meridian as a positive or
3588	   negative real number, respectively. The latitude represents the
3589	   location north and south of the equator as a positive or negative
3590	   real number, respectively. The longitude and latitude values MUST be
3591	   specified as decimal degrees and should be specified to six decimal
3592	   places. This will allow for granularity within a meter of the
3593	   geographical position. The simple formula for converting degrees-
3594	   minutes-seconds into decimal degrees is:

3596	     decimal = degrees + minutes/60 + seconds/3600.

3598	   Format Definition: The property is defined by the following notation:

3600	     geo        = "GEO" geoparam ":" geovalue CRLF

3602	     geoparam   = *(";" xparam)

3604	     geovalue   = float ";" float
3605	     ;Latitude and Longitude components

3607	   Example: The following is an example of this property:

3609	     GEO:37.386013;-122.082932

3611	4.8.1.7 Location

3613	   Property Name: LOCATION

3615	   Purpose: The property defines the intended venue for the activity
3616	   defined by a calendar component.

3618	   Value Type: TEXT

3620	   Property Parameters: Non-standard, alternate text representation and
3621	   language property parameters can be specified on this property.

3623	   Conformance: This property can be specified in the "VEVENT" or
3624	   "VTODO" calendar component.

3626	   Description: Specific venues such as conference or meeting rooms may
3627	   be explicitly specified using this property. An alternate
3628	   representation may be specified that is a URI that points to
3629	   directory information with more structured specification of the
3630	   location. For example, the alternate representation may specify
3631	   either an LDAP URI pointing to an LDAP server entry or a CID URI
3632	   pointing to a MIME body part containing a vCard for the location.

3634	   Format Definition: The property is defined by the following notation:

3636	     location   = "LOCATION locparam ":" text CRLF

3638	     locparam   = [";" altrepparam] [";" languageparam]
3639	                  *(";" xparam)

3641	   Example: The following are some examples of this property:

3643	     LOCATION:Conference Room - F123, Bldg. 002

3645	     LOCATION;ALTREP="http://xyzcorp.com/conf-rooms/f123.vcf":
3646	      Conference Room - F123, Bldg. 002

3648	4.8.1.8 Percent Complete

3650	   Property Name: PERCENT-COMPLETE

3652	   Purpose: This property is used by an assignee or delegatee of a to-do
3653	   to convey the percent completion of a to-do to the Organizer.

3655	   Value Type: INTEGER

3657	   Property Parameters: Non-standard property parameters can be
3658	   specified on this property.

3660	   Conformance: This property can be specified in a "VTODO" calendar
3661	   component.

3663	   Description: The property value is a positive integer between zero
3664	   and one hundred. A value of "0" indicates the to-do has not yet been
3665	   started. A value of "100" indicates that the to-do has been
3666	   completed. Integer values in between indicate the percent partially
3667	   complete.

3669	   When a to-do is assigned to multiple individuals, the property value
3670	   indicates the percent complete for that portion of the to-do assigned
3671	   to the assignee or delegatee. For example, if a to-do is assigned to
3672	   both individuals "A" and "B". A reply from "A" with a percent
3673	   complete of "70" indicates that "A" has completed 70% of the to-do
3674	   assigned to them. A reply from "B" with a percent complete of "50"
3675	   indicates "B" has completed 50% of the to-do assigned to them.

3677	   Format Definition: The property is defined by the following notation:

3679	     percent = "PERCENT-COMPLETE" pctparam ":" integer CRLF

3681	     pctparam   = *(";" xparam)

3683	   Example: The following is an example of this property to show 39%
3684	   completion:

3686	     PERCENT-COMPLETE:39

3688	4.8.1.9 Priority

3690	   Property Name: PRIORITY

3692	   Purpose: The property defines the relative priority for a calendar
3693	   component.

3695	   Value Type: INTEGER

3697	   Property Parameters: Non-standard property parameters can be
3698	   specified on this property.

3700	   Conformance: The property can be specified in a "VEVENT" or "VTODO"
3701	   calendar component.

3703	   Description: The priority is specified as an integer in the range
3704	   zero to nine. A value of zero (US-ASCII decimal 48) specifies an
3705	   undefined priority. A value of one (US-ASCII decimal 49) is the
3706	   highest priority. A value of two (US-ASCII decimal 50) is the second
3707	   highest priority. Subsequent numbers specify a decreasing ordinal
3708	   priority. A value of nine (US-ASCII decimal 58) is the lowest
3709	   priority.

3711	   A CUA with a three-level priority scheme of "HIGH", "MEDIUM" and
3712	   "LOW" is mapped into this property such that a property value in the
3713	   range of one (US-ASCII decimal 49) to four (US-ASCII decimal 52)
3714	   specifies "HIGH" priority. A value of five (US-ASCII decimal 53) is
3715	   the normal or "MEDIUM" priority. A value in the range of six (US-
3716	   ASCII decimal 54) to nine (US-ASCII decimal 58) is "LOW" priority.

3718	   A CUA with a priority schema of "A1", "A2", "A3", "B1", "B2", ...,
3719	   "C3" is mapped into this property such that a property value of one
3720	   (US-ASCII decimal 49) specifies "A1", a property value of two (US-
3721	   ASCII decimal 50) specifies "A2", a property value of three (US-ASCII
3722	   decimal 51) specifies "A3", and so forth up to a property value of 9
3723	   (US-ASCII decimal 58) specifies "C3".

3725	   Other integer values are reserved for future use.

3727	   Within a "VEVENT" calendar component, this property specifies a
3728	   priority for the event. This property may be useful when more than
3729	   one event is scheduled for a given time period.

3731	   Within a "VTODO" calendar component, this property specified a
3732	   priority for the to-do. This property is useful in prioritizing
3733	   multiple action items for a given time period.

3735	   Format Definition: The property is specified by the following
3736	   notation:

3738	     priority   = "PRIORITY" prioparam ":" privalue CRLF
3739	     ;Default is zero

3741	     prioparam  = *(";" xparam)

3743	     privalue   = integer       ;Must be in the range [0..9]
3744	        ; All other values are reserved for future use

3746	   The following is an example of a property with the highest priority:

3748	     PRIORITY:1

3750	   The following is an example of a property with a next highest
3751	   priority:

3753	     PRIORITY:2

3755	   Example: The following is an example of a property with no priority.
3756	   This is equivalent to not specifying the "PRIORITY" property.:

3758	     PRIORITY:0
3759	4.8.1.10        Resources

3761	   Property Name: RESOURCES

3763	   Purpose: This property defines the equipment or resources anticipated
3764	   for an activity specified by a calendar entity..

3766	   Value Type: TEXT

3768	   Property Parameters: Non-standard, alternate text representation and
3769	   language property parameters can be specified on this property.

3771	   Conformance: This property can be specified in a "VEVENT" or "VTODO"
3772	   calendar component.

3774	   Description: The property value is an arbitrary text. More than one
3775	   resource can be specified as a list of resources separated by the
3776	   COMMA character (US-ASCII decimal 44).

3778	   Format Definition: The property is defined by the following notation:

3780	     resources  = "RESOURCES" resrcparam ":" text *("," text) CRLF

3782	     resrcparam = [";" altrepparam] [";" languageparam]
3783	                  *(";" xparam)

3785	   Example: The following is an example of this property:

3787	     RESOURCES:EASEL,PROJECTOR,VCR

3789	     RESOURCES;LANGUAGE=fr:1 raton-laveur

3791	4.8.1.11        Status

3793	   Property Name: STATUS

3795	   Purpose: This property defines the overall status or confirmation for
3796	   the calendar component.

3798	   Value Type: TEXT

3800	   Property Parameters: Non-standard property parameters can be
3801	   specified on this property.

3803	   Conformance: This property can be specified in the "VEVENT", "VTODO"
3804	   and "VJOURNAL" calendar components.

3806	   Description: In a group scheduled calendar component, the property is
3807	   used by the "Organizer" to provide a confirmation of the event to the
3808	   "Attendees". For example in a "VEVENT" calendar component, the
3809	   "Organizer" can indicate that a meeting is tentative, confirmed or
3810	   cancelled. In a "VTODO" calendar component, the "Organizer" can
3811	   indicate that an action item needs action, is completed, is in
3812	   process or being worked on, or has been cancelled. In a "VJOURNAL"
3813	   calendar component, the "Organizer" can indicate that a journal entry
3814	   is draft, final or has been cancelled or removed.

3816	   Format Definition: The property is defined by the following notation:

3818	     status     = "STATUS" statparam] ":" statvalue CRLF

3820	     statparam  = *(";" xparam)

3822	     statvalue  = "TENTATIVE"           ;Indicates event is
3823	                                        ;tentative.
3824	                / "CONFIRMED"           ;Indicates event is
3825	                                        ;definite.
3826	                / "CANCELLED"           ;Indicates event was
3827	                                        ;cancelled.
3828	        ;Status values for a "VEVENT"

3830	     statvalue  =/ "NEEDS-ACTION"       ;Indicates to-do needs action.
3831	                / "COMPLETED"           ;Indicates to-do completed.
3832	                / "IN-PROCESS"          ;Indicates to-do in process of
3833	                / "CANCELLED"           ;Indicates to-do was cancelled.
3834	        ;Status values for "VTODO".

3836	     statvalue  =/ "DRAFT"              ;Indicates journal is draft.
3837	                / "FINAL"               ;Indicates journal is final.
3838	                / "CANCELLED"           ;Indicates journal is removed.
3839	        ;Status values for "VJOURNAL".

3841	   Example: The following is an example of this property for a "VEVENT"
3842	   calendar component:

3844	     STATUS:TENTATIVE

3846	   The following is an example of this property for a "VTODO" calendar
3847	   component:

3849	     STATUS:NEEDS-ACTION

3851	   The following is an example of this property for a "VJOURNAL"
3852	   calendar component:

3854	     STATUS:DRAFT

3856	4.8.1.12        Summary

3858	   Property Name: SUMMARY

3860	   Purpose: This property defines a short summary or subject for the
3861	   calendar component.

3863	   Value Type: TEXT

3865	   Property Parameters: Non-standard, alternate text representation and
3866	   language property parameters can be specified on this property.

3868	   Conformance: The property can be specified in the "VEVENT", "VTODO",
3869	   "VJOURNAL" and "VALARM" calendar components.

3871	   Description: This property is used in the "VEVENT", "VTODO" and
3872	   "VJOURNAL" calendar components to capture a short, one line summary
3873	   about the activity or journal entry.

3875	   This property is used in the "VALARM" calendar component to capture
3876	   the subject of an EMAIL category of alarm.

3878	   Format Definition: The property is defined by the following notation:

3880	     summary    = "SUMMARY" summparam ":" text CRLF

3882	     summparam  = [";" altrepparam] [";" languageparam]
3883	                  *(";" xparam)

3885	   Example: The following is an example of this property:

3887	     SUMMARY:Department Party

3889	4.8.2   Date and Time Component Properties

3891	   The following properties specify date and time related information in
3892	   calendar components.

3894	4.8.2.1 Date/Time Completed

3896	   Property Name: COMPLETED

3898	   Purpose: This property defines the date and time that a to-do was
3899	   actually completed.

3901	   Value Type: DATE-TIME

3903	   Property Parameters: Non-standard property parameters can be
3904	   specified on this property.

3906	   Conformance: The property can be specified in a "VTODO" calendar
3907	   component.

3909	   Description: The date and time must be in a UTC format.

3911	   Format Definition: The property is defined by the following notation:

3913	     completed  = "COMPLETED" compparam ":" date-time CRLF

3915	     compparam  = *(";" xparam)

3917	   Example: The following is an example of this property:

3919	     COMPLETED:19960401T235959Z
3920	4.8.2.2 Date/Time End

3922	   Property Name: DTEND

3924	   Purpose: This property specifies the date and time that a calendar
3925	   component ends.

3927	   Value Type: The default value type is DATE-TIME. The value type can
3928	   be reset to a DATE value type.

3930	   Property Parameters: Non-standard, value data type, time zone
3931	   identifier property parameters can be specified on this property.

3933	   Conformance: This property can be specified within the "VEVENT" and
3934	   "VFREEBUSY" calendar components.

3936	   Description: Within the "VEVENT" calendar component, this property
3937	   defines the date and time by which the event ends. The value MUST be
3938	   later in time than the value of the "DTSTART" property.

3940	   Within the "VFREEBUSY" calendar component, this property defines the
3941	   end date and time for the free or busy time information. The time
3942	   MUST be specified as in the UTC time format. The value MUST be later
3943	   in time than the value of the "DTSTART" property.

3945	   Format Definition: The property is defined by the following notation:

3947	     dtend      = "DTEND" dtendparam":" dtendval CRLF

3949	     dtendparam = [";" "VALUE" "=" ("DATE-TIME" / "DATE")]
3950	                  [";" tzidparam]
3951	                  *(";" xparam)

3953	     dtendval   = date-time / date
3954	     ;Value MUST match value type

3956	   Example: The following is an example of this property:

3958	     DTEND:19960401T235959Z

3960	     DTEND;VALUE=DATE:19980704

3962	4.8.2.3 Date/Time Due

3964	   Property Name: DUE

3966	   Purpose: This property defines the date and time that a to-do is
3967	   expected to be completed.

3969	   Value Type: The default value type is DATE-TIME. The value type can
3970	   be reset to a DATE value type.

3972	   Property Parameters: Non-standard, value data type, time zone
3973	   identifier property parameters can be specified on this property.

3975	   Conformance: The property can be specified once within a "VTODO"
3976	   calendar component.

3978	   Description: The value MUST be a date/time equal to or after the
3979	   DTSTART value, if specified.

3981	   Format Definition: The property is defined by the following notation:

3983	     due        = "DUE" dueparam":" dueval CRLF

3985	     dueparam   = [";" "VALUE" "=" ("DATE-TIME" / "DATE")]
3986	                  [";" tzidparam]
3987	                  *(";" xparam)

3989	     dueval     = date-time / date
3990	     ;Value MUST match value type

3992	   Example: The following is an example of this property:

3994	     DUE:19980430T235959Z

3996	4.8.2.4 Date/Time Start

3998	   Property Name: DTSTART

4000	   Purpose: This property specifies when the calendar component begins.

4002	   Value Type: The default value type is DATE-TIME. The time value MUST
4003	   be one of the forms defined for the DATE-TIME value type. The value
4004	   type can be reset to a DATE value type.

4006	   Property Parameters: Non-standard, value data type, time zone
4007	   identifier property parameters can be specified on this property.

4009	   Conformance: This property can be specified within the "VEVENT",
4010	   "VTODO", "VFREEBUSY", and "VTIMEZONE" calendar components.

4012	   Description: Within the "VEVENT" calendar component, this property
4013	   defines the start date and time for the event. The property is
4014	   REQUIRED in "VEVENT" calendar components. Events can have a start
4015	   date/time but no end date/time. In that case, the event does not take
4016	   up any time.

4018	   Within the "VFREEBUSY" calendar component, this property defines the
4019	   start date and time for the free or busy time information. The time
4020	   MUST be specified in UTC time.

4022	   Within the "VTIMEZONE" calendar component, this property defines the
4023	   effective start date and time for a time zone specification. This
4024	   property is REQUIRED within each STANDARD and DAYLIGHT part included
4025	   in "VTIMEZONE" calendar components and MUST be specified as a local
4026	   DATE-TIME without the "TZID" property parameter.

4028	   Format Definition: The property is defined by the following notation:

4030	     dtstart    = "DTSTART" dtstparam ":" dtstval CRLF

4032	     dtstparam  = [";" "VALUE" "=" ("DATE-TIME" / "DATE")]
4033	                  [";" tzidparam]
4034	                  *(";" xparam)

4036	     dtstval    = date-time / date
4037	     ;Value MUST match value type

4039	   Example: The following is an example of this property:

4041	     DTSTART:19980118T073000Z

4043	4.8.2.5 Duration

4045	   Property Name: DURATION

4047	   Purpose: The property specifies a positive duration of time .

4049	   Value Type: DURATION

4051	   Property Parameters: Non-standard property parameters can be
4052	   specified on this property.

4054	   Conformance: The property can be specified in a "VEVENT", "VTODO",
4055	   "VFREEBUSY" and "VALARM" calendar components.

4057	   Description: In a "VEVENT" calendar component the property may be
4058	   used to specify a duration of the event, instead of an explicit end
4059	   date/time. In a "VTODO" calendar component the property may be used
4060	   to specify a duration for the to-do, instead of an explicit due
4061	   date/time. In a "VFREEBUSY" calendar component the property may be
4062	   used to specify the interval of free time being requested. In a
4063	   "VALARM" calendar component the property may be used to specify the
4064	   delay period prior to repeating an alarm.

4066	   Format Definition: The property is defined by the following notation:

4068	     duration   = "DURATION" durparam ":" duration CRLF
4069	                  ;consisting of a positive duration of time.

4071	     durparam   = *(";" xparam)

4073	   Example: The following is an example of this property that specifies
4074	   an interval of time of 1 hour and zero minutes and zero seconds:

4076	     DURATION:PT1H0M0S

4078	   The following is an example of this property that specifies an
4079	   interval of time of 15 minutes.

4081	     DURATION:PT15M
4082	4.8.2.6 Free/Busy Time

4084	   Property Name: FREEBUSY

4086	   Purpose: The property defines one or more free or busy time
4087	   intervals.

4089	   Value Type: PERIOD. The date and time values MUST be in an UTC time
4090	   format.

4092	   Property Parameters: Non-standard or free/busy time type property
4093	   parameters can be specified on this property.

4095	   Conformance: The property can be specified in a "VFREEBUSY" calendar
4096	   component.

4098	   Property Parameter: "FBTYPE" and non-standard parameters can be
4099	   specified on this property.

4101	   Description: These time periods can be specified as either a start
4102	   and end date-time or a start date-time and duration. The date and
4103	   time MUST be a UTC time format.

4105	   "FREEBUSY" properties within the "VFREEBUSY" calendar component
4106	   should be sorted in ascending order, based on start time and then end
4107	   time, with the earliest periods first.

4109	   The "FREEBUSY" property can specify more than one value, separated by
4110	   the COMMA character (US-ASCII decimal 44). In such cases, the
4111	   "FREEBUSY" property values should all be of the same "FBTYPE"
4112	   property parameter type (e.g., all values of a particular "FBTYPE"
4113	   listed together in a single property).

4115	   Format Definition: The property is defined by the following notation:

4117	     freebusy   = "FREEBUSY" fbparam ":" fbvalue
4118	                  CRLF

4120	     fbparam    = [";" fbtypeparam] *(";" xparam)

4122	     fbvalue    = period *["," period]
4123	     ;Time value MUST be in the UTC time format.

4125	   Example: The following are some examples of this property:

4127	     FREEBUSY;FBTYPE=BUSY-UNAVAILABLE:19970308T160000Z/PT8H30M

4129	     FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H

4131	     FREEBUSY;FBTYPE=FREE:19970308T160000Z/PT3H,19970308T200000Z/PT1H,
4132	      19970308T230000Z/19970309T000000Z
4133	4.8.2.7 Time Transparency

4135	   Property Name: TRANSP

4137	   Purpose: This property defines whether an event is transparent or not
4138	   to busy time searches.

4140	   Value Type: TEXT

4142	   Property Parameters: Non-standard property parameters can be
4143	   specified on this property.

4145	   Conformance: This property can be specified once within a "VEVENT"
4146	   calendar component.

4148	   Description: Transparency is the state that determines whether an
4149	   event takes up time on a calendar, and with be reflected as "busy
4150	   time", or is just "penciled in" to the calendar, and will not be
4151	   reflected as "busy time". If the event is transparent, then other
4152	   events can be scheduled in the same time period without there being a
4153	   time period conflict. If not specified, the default state is OPAQUE.

4155	   Format Definition: The property is specified by the following
4156	   notation:

4158	     transp     = "TRANSP" tranparam ":" transvalue CRLF

4160	     tranparam  = *(";" xparam)

4162	     transvalue = "OPAQUE"      ;Blocks or opaque on busy time searches.
4163	                / "TRANSPARENT" ;Transparent on busy time searches.
4164	        ;Default value is OPAQUE

4166	   Example: The following is an example of this property for an event
4167	   that is transparent or does not block on free/busy time searches:

4169	     TRANSP:TRANSPARENT

4171	   The following is an example of this property for an event that is
4172	   opaque or blocks on free/busy time searches:

4174	     TRANSP:OPAQUE

4176	4.8.3   Time Zone Component Properties

4178	   The following properties specify time zone information in calendar
4179	   components.

4181	4.8.3.1 Time Zone Identifier

4183	   Property Name: TZID

4185	   Purpose: This property specifies the text value that uniquely
4186	   identifies the "VTIMEZONE" calendar component.

4188	   Value Type: TEXT

4190	   Property Parameters: Non-standard property parameters can be
4191	   specified on this property.

4193	   Conformance: This property MUST be specified in a "VTIMEZONE"
4194	   calendar component.

4196	   Description: This is the label by which a time zone calendar
4197	   component is referenced by any iCalendar properties whose data type
4198	   is either DATE-TIME or TIME and not intended to specify a UTC or
4199	   a"floating" time. The presence of the SOLIDUS character (US-ASCII
4200	   decimal 47) as a prefix, indicates that this TZID represents an
4201	   unique ID in a globally defined time zone registry (when such
4202	   registry is defined).

4204	   Format Definition: This property is defined by the following
4205	   notation:

4207	     tzid       = "TZID" tzidpropparam ":" [tzidprefix] text CRLF

4209	     tzidpropparam      = *(";" xparam)

4211	     ;tzidprefix        = "/"
4212	     ; Defined previously. Just listed here for reader convenience.

4214	   Example: The following are examples of non-globally unique time zone
4215	   identifiers:

4217	     TZID:America-New_York

4219	     TZID:California-Los_Angeles

4221	   The following is an example of a globally unique time zone
4222	   identifier:

4224	     TZID:/US-New_York-New_York

4226	4.8.3.2 Time Zone Name

4228	   Property Name: TZNAME

4230	   Purpose: This property specifies the customary designation for a time
4231	   zone description.

4233	   Value Type: TEXT

4235	   Property Parameters: Non-standard and language property parameters
4236	   can be specified on this property.

4238	   Conformance: This property can be specified in the "VTIMEZONE"
4239	   calendar component.

4241	   Description: This property may be specified in multiple languages; in
4242	   order to provide for different language requirements.

4244	   Format Definition: This property is defined by the following
4245	   notation:

4247	     tzname     = "TZNAME" tznparam ":" text CRLF

4249	     tznparam   = [";" languageparm]
4250	                  *(";" xparam)

4252	   Example: The following are example of this property:

4254	     TZNAME:EST

4256	   The following is an example of this property when two different
4257	   languages for the time zone name are specified:

4259	     TZNAME;LANGUAGE=en:EST
4260	     TZNAME;LANGUAGE=fr-CA:HNE

4262	4.8.3.3 Time Zone Offset From

4264	   Property Name: TZOFFSETFROM

4266	   Purpose: This property specifies the offset which is in use prior to
4267	   this time zone observance.

4269	   Value Type: UTC-OFFSET

4271	   Property Parameters: Non-standard property parameters can be
4272	   specified on this property.

4274	   Conformance: This property MUST be specified in a "VTIMEZONE"
4275	   calendar component.

4277	   Description: This property specifies the offset which is in use prior
4278	   to this time observance. It is used to calculate the absolute time at
4279	   which the transition to a given observance takes place. This property
4280	   MUST only be specified in a "VTIMEZONE" calendar component. A
4281	   "VTIMEZONE" calendar component MUST include this property. The
4282	   property value is a signed numeric indicating the number of hours and
4283	   possibly minutes from UTC. Positive numbers represents time zones
4284	   east of the prime meridian, or ahead of UTC. Negative numbers
4285	   represents time zones west of the prime meridian, or behind UTC.

4287	   Format Definition: The property is defined by the following notation:

4289	     tzoffsetfrom       = "TZOFFSETFROM" frmparam ":" utc-offset
4290	                          CRLF

4292	     frmparam   = *(";" xparam)

4294	   Example: The following are examples of this property:

4296	     TZOFFSETFROM:-0500

4298	     TZOFFSETFROM:+1345

4300	4.8.3.4 Time Zone Offset To

4302	   Property Name: TZOFFSETTO

4304	   Purpose: This property specifies the offset which is in use in this
4305	   time zone observance.

4307	   Value Type: UTC-OFFSET

4309	   Property Parameters: Non-standard property parameters can be
4310	   specified on this property.

4312	   Conformance: This property MUST be specified in a "VTIMEZONE"
4313	   calendar component.

4315	   Description: This property specifies the offset which is in use in
4316	   this time zone observance. It is used to calculate the absolute time
4317	   for the new observance. The property value is a signed numeric
4318	   indicating the number of hours and possibly minutes from UTC.
4319	   Positive numbers represents time zones east of the prime meridian, or
4320	   ahead of UTC. Negative numbers represents time zones west of the
4321	   prime meridian, or behind UTC.

4323	   Format Definition: The property is defined by the following notation:

4325	     tzoffsetto = "TZOFFSETTO" toparam ":" utc-offset CRLF

4327	     toparam    = *(";" xparam)

4329	   Example: The following are examples of this property:

4331	     TZOFFSETTO:-0400

4333	     TZOFFSETTO:+1245

4335	4.8.3.5 Time Zone URL

4337	   Property Name: TZURL

4339	   Purpose: The TZURL provides a means for a VTIMEZONE component to
4340	   point to a network location that can be used to retrieve an up-to-
4341	   date version of itself.

4343	   Value Type: URI

4345	   Property Parameters: Non-standard property parameters can be
4346	   specified on this property.

4348	   Conformance: This property can be specified in a "VTIMEZONE" calendar
4349	   component.

4351	   Description: The TZURL provides a means for a VTIMEZONE component to
4352	   point to a network location that can be used to retrieve an up-to-
4353	   date version of itself.  This provides a hook to handle changes
4354	   government bodies impose upon time zone definitions.  Retrieval of
4355	   this resource results in an iCalendar object containing a single
4356	   VTIMEZONE component and a METHOD property set to PUBLISH.

4358	   Format Definition: The property is defined by the following notation:

4360	     tzurl      = "TZURL" tzurlparam ":" uri CRLF

4362	     tzurlparam = *(";" xparam)

4364	   Example: The following is an example of this property:

4366	     TZURL:http://timezones.r.us.net/tz/US-California-Los_Angeles

4368	4.8.4   Relationship Component Properties

4370	   The following properties specify relationship information in calendar
4371	   components.

4373	4.8.4.1 Attendee

4375	   Property Name: ATTENDEE

4377	   Purpose: The property defines an "Attendee" within a calendar
4378	   component.

4380	   Value Type: CAL-ADDRESS

4382	   Property Parameters: Non-standard, language, calendar user type,
4383	   group or list membership, participation role, participation status,
4384	   RSVP expectation, delegatee, delegator, sent by, common name or
4385	   directory entry reference property parameters can be specified on
4386	   this property.

4388	   Conformance: This property MUST be specified in an iCalendar object
4389	   that specifies a group scheduled calendar entity. This property MUST
4390	   NOT be specified in an iCalendar object when publishing the calendar
4391	   information (e.g., NOT in an iCalendar object that specifies the
4392	   publication of a calendar user's busy time, event, to-do or journal).
4393	   This property is not specified in an iCalendar object that specifies
4394	   only a time zone definition or that defines calendar entities that
4395	   are not group scheduled entities, but are entities only on a single
4396	   user's calendar.

4398	   Description: The property is MUST only be specified within calendar
4399	   components to specify participants, non-participants and the chair of
4400	   a group scheduled calendar entity. The property is specified within
4401	   an "EMAIL" category of the "VALARM" calendar component to specify an
4402	   email address that is to receive the email type of iCalendar alarm.

4404	   The property parameter CN, is for the common or displayable name
4405	   associated with the calendar address; ROLE, for the intended role
4406	   that the attendee will have in the calendar component; PARTSTAT, for
4407	   the status of the attendee's participation; RSVP, for indicating
4408	   whether the favor of a reply is requested; CUTYPE, to indicate the
4409	   type of calendar user; MEMBER, to indicate the groups that the
4410	   attendee belongs to; DELEGATED-TO, to indicate the calendar users
4411	   that the original request was delegated to; and DELEGATED-FROM, to
4412	   indicate whom the request was delegated from; SENT-BY, to indicate
4413	   whom is acting on behalf of the ATTENDEE; and DIR, to indicate the
4414	   URI that points to the directory information corresponding to the
4415	   attendee. These property parameters can be specified on an "ATTENDEE"
4416	   property in either a "VEVENT", "VTODO" or "VJOURNAL" calendar
4417	   component. They MUST not be specified in an "ATTENDEE" property in a
4418	   "VFREEBUSY" or "VALARM" calendar component. If the LANGUAGE property
4419	   parameter is specified, the identified language applies to the CN
4420	   parameter.

4422	   A recipient delegated a request MUST inherit the RSVP and ROLE values
4423	   from the attendee that delegated the request to them.

4425	   Multiple attendees can be specified by including multiple "ATTENDEE"
4426	   properties within the calendar component.

4428	   Format Definition: The property is defined by the following notation:

4430	     attendee   = "ATTENDEE" attparam ":" cal-address CRLF

4432	     attparam   = [";" cutypeparam] [";"memberparam] [";" roleparam]
4433	                  [";" partstatparam] [";" rsvpparam] [";" deltoparam]
4434	                  [";" delfromparam] [";" sentbyparam] [";"cnparam]
4435	                  [";" dirparam] [";" languageparam] *(";" xparam)

4437	   Example: The following are examples of this property's use for a to-
4438	   do:

4440	     ORGANIZER:MAILTO:jsmith@host1.com
4441	     ATTENDEE;MEMBER="MAILTO:DEV-GROUP@host2.com":
4442	      MAILTO:joecool@host2.com
4443	     ATTENDEE;DELEGATED-FROM="MAILTO:immud@host3.com":
4444	      MAILTO:ildoit@host1.com

4446	   The following is an example of this property used for specifying
4447	   multiple attendees to an event:

4449	     ORGANIZER:MAILTO:jsmith@host1.com
4450	     ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;CN=Henry Cabot
4451	      :MAILTO:hcabot@host2.com
4452	     ATTENDEE;ROLE=REQ-PARTICIPANT;DELEGATED-FROM="MAILTO:bob@host.com"
4453	      ;PARTSTAT=ACCEPTED;CN=Jane Doe:MAILTO:jdoe@host1.com

4455	   The following is an example of this property with a URI to the
4456	   directory information associated with the attendee:

4458	     ATTENDEE;CN=John Smith;DIR="ldap://host.com:6666/o=eDABC%
4459	      20Industries,c=3DUS??(cn=3DBJim%20Dolittle)":MAILTO:jimdo@
4460	      host1.com

4462	   The following is an example of this property with "delegatee" and
4463	   "delegator" information for an event:

4465	     ORGANIZER;CN=John Smith:MAILTO:jsmith@host.com
4466	     ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=TENTATIVE;DELEGATED-FROM=
4467	      "MAILTO:iamboss@host2.com";CN=Henry Cabot:MAILTO:hcabot@
4468	      host2.com
4469	     ATTENDEE;ROLE=NON-PARTICIPANT;PARTSTAT=DELEGATED;DELEGATED-TO=
4470	      "MAILTO:hcabot@host2.com";CN=The Big Cheese:MAILTO:iamboss
4471	      @host2.com
4472	     ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=ACCEPTED;CN=Jane Doe
4473	      :MAILTO:jdoe@host1.com

4475	   Example: The following is an example of this property's use when
4476	   another calendar user is acting on behalf of the "Attendee":

4478	     ATTENDEE;SENT-BY=MAILTO:jan_doe@host1.com;CN=John Smith:MAILTO:
4479	      jsmith@host1.com

4481	4.8.4.2 Contact

4483	   Property Name: CONTACT

4485	   Purpose: The property is used to represent contact information or
4486	   alternately a reference to contact information associated with the
4487	   calendar component.

4489	   Value Type: TEXT

4491	   Property Parameters: Non-standard, alternate text representation and
4492	   language property parameters can be specified on this property.

4494	   Conformance: The property can be specified in a "VEVENT", "VTODO",
4495	   "VJOURNAL" and "VFREEBUSY" calendar component.

4497	   Description: The property value consists of textual contact
4498	   information. An alternative representation for the property value can
4499	   also be specified that refers to a URI pointing to an alternate form,
4500	   such as a vCard, for the contact information.

4502	   Format Definition: The property is defined by the following notation:

4504	     contact    = "CONTACT" contparam ":" text CRLF

4506	     contparam  = [";" altrepparam] [";" languageparam]
4507	                  *(";" xparam)

4509	   Example: The following is an example of this property referencing
4510	   textual contact information:

4512	     CONTACT:Jim Dolittle\, ABC Industries\, +1-919-555-1234

4514	   The following is an example of this property with an alternate
4515	   representation of a LDAP URI to a directory entry containing the
4516	   contact information:

4518	     CONTACT;ALTREP="ldap://host.com:6666/o=3DABC%20Industries\,
4519	      c=3DUS??(cn=3DBJim%20Dolittle)":Jim Dolittle\, ABC Industries\,
4520	      +1-919-555-1234

4522	   The following is an example of this property with an alternate
4523	   representation of a MIME body part containing the contact
4524	   information, such as a vCard embedded in a [MIME-DIR] content-type:

4526	     CONTACT;ALTREP="CID=<part3.msg970930T083000SILVER@host.com>":Jim
4527	       Dolittle\, ABC Industries\, +1-919-555-1234

4529	   The following is an example of this property referencing a network
4530	   resource, such as a vCard object containing the contact information:

4532	     CONTACT;ALTREP="http://host.com/pdi/jdoe.vcf":Jim
4533	       Dolittle\, ABC Industries\, +1-919-555-1234

4535	4.8.4.3 Organizer

4537	   Property Name: ORGANIZER

4539	   Purpose: The property defines the organizer for a calendar component.

4541	   Value Type: CAL-ADDRESS

4543	   Property Parameters: Non-standard, language, common name, directory
4544	   entry reference, sent by property parameters can be specified on this
4545	   property.

4547	   Conformance: This property MUST be specified in an iCalendar object
4548	   that specifies a group scheduled calendar entity. This property MUST
4549	   be specified in an iCalendar object that specifies the publication of
4550	   a calendar user's busy time. This property MUST NOT be specified in
4551	   an iCalendar object that specifies only a time zone definition or
4552	   that defines calendar entities that are not group scheduled entities,
4553	   but are entities only on a single user's calendar.

4555	   Description: The property is specified within the "VEVENT", "VTODO",
4556	   "VJOURNAL calendar components to specify the organizer of a group
4557	   scheduled calendar entity. The property is specified within the
4558	   "VFREEBUSY" calendar component to specify the calendar user
4559	   requesting the free or busy time. When publishing a "VFREEBUSY"
4560	   calendar component, the property is used to specify the calendar that
4561	   the published busy time came from.

4563	   The property has the property parameters CN, for specifying the
4564	   common or display name associated with the "Organizer", DIR, for
4565	   specifying a pointer to the directory information associated with the
4566	   "Organizer", SENT-BY, for specifying another calendar user that is
4567	   acting on behalf of the "Organizer". The non-standard parameters may
4568	   also be specified on this property. If the LANGUAGE property
4569	   parameter is specified, the identified language applies to the CN
4570	   parameter value.

4572	   Format Definition: The property is defined by the following notation:

4574	     organizer  = "ORGANIZER" orgparam ":"
4575	                  cal-address CRLF

4577	     orgparam   = [";" cnparam] [";" dirparam] [";" sentbyparam]
4578	                  [";" languageparam] *(";" xparam)

4580	   Example: The following is an example of this property:

4582	     ORGANIZER;CN=John Smith:MAILTO:jsmith@host1.com

4584	   The following is an example of this property with a pointer to the
4585	   directory information associated with the organizer:

4587	     ORGANIZER;CN=JohnSmith;DIR="ldap://host.com:6666/o=3DDC%20Associ
4588	      ates,c=3DUS??(cn=3DJohn%20Smith)":MAILTO:jsmith@host1.com

4590	   The following is an example of this property used by another calendar
4591	   user who is acting on behalf of the organizer, with responses
4592	   intended to be sent back to the organizer, not the other calendar
4593	   user:

4595	     ORGANIZER;SENT-BY="MAILTO:jane_doe@host.com":
4596	      MAILTO:jsmith@host1.com

4598	4.8.4.4 Recurrence ID

4600	   Property Name: RECURRENCE-ID

4602	   Purpose: This property is used in conjunction with the "UID" and
4603	   "SEQUENCE" property to identify a specific instance of a recurring
4604	   "VEVENT", "VTODO" or "VJOURNAL" calendar component. The property
4605	   value is the effective value of the "DTSTART" property of the
4606	   recurrence instance.

4608	   Value Type: The default value type for this property is DATE-TIME.
4609	   The time format can be any of the valid forms defined for a DATE-TIME
4610	   value type. See DATE-TIME value type definition for specific
4611	   interpretations of the various forms. The value type can be reset to
4612	   DATE.

4614	   Property Parameters: Non-standard property, value data type, time
4615	   zone identifier and recurrence identifier range parameters can be
4616	   specified on this property.

4618	   Conformance: This property can be specified in an iCalendar object
4619	   containing a recurring calendar component.

4621	   Description: The full range of calendar components specified by a
4622	   recurrence set is referenced by referring to just the "UID" property
4623	   value corresponding to the calendar component. The "RECURRENCE-ID"
4624	   property allows the reference to an individual instance within the
4625	   recurrence set.

4627	   If the value of the "DTSTART" property is a DATE type value, then the
4628	   value MUST be the calendar date for the recurrence instance.

4630	   The date/time value is set to the time when the original recurrence
4631	   instance would occur - - meaning that if the intent is to change a
4632	   Friday meeting to Thursday, the date/time is still set to the
4633	   original Friday meeting.

4635	   The "RECURRENCE-ID" property is used in conjunction with the "UID"
4636	   and "SEQUENCE" property to identify a particular instance of a
4637	   recurring event, to-do or journal. For a given pair of "UID" and
4638	   "SEQUENCE" property values, the "RECURRENCE-ID" value for a
4639	   recurrence instance is fixed. When the definition of the recurrence
4640	   set for a calendar component changes, and hence the "SEQUENCE"
4641	   property value changes, the "RECURRENCE-ID" for a given recurrence
4642	   instance might also change.The "RANGE" parameter is used to specify
4643	   the effective range of recurrence instances from the instance
4644	   specified by the "RECURRENCE-ID" property value. The default value
4645	   for the range parameter is the single recurrence instance only. The
4646	   value can also be "THISANDPRIOR" to indicate a range defined by the
4647	   given recurrence instance and all prior instances or the value can be
4648	   "THISANDFUTURE" to indicate a range defined by the given recurrence
4649	   instance and all subsequent instances.

4651	   Format Definition: The property is defined by the following notation:

4653	     recurid    = "RECURRENCE-ID" ridparam ":" ridval CRLF

4655	     ridparam   = [";" "VALUE" "=" ("DATE-TIME" / "DATE)]
4656	                  [";" tzidparam] [";" rangeparam]
4657	                  *(";" xparam)

4659	     ridval     = date-time / date
4660	     ;Value MUST match value type

4662	   Example: The following are examples of this property:

4664	     RECURRENCE-ID;VALUE=DATE:19960401

4666	     RECURRENCE-ID;RANGE=THISANDFUTURE:19960120T120000Z

4668	4.8.4.5 Related To

4670	   Property Name: RELATED-TO

4672	   Purpose: The property is used to represent a relationship or
4673	   reference between one calendar component and another.

4675	   Value Type: TEXT

4677	   Property Parameters: Non-standard and relationship type property
4678	   parameters can be specified on this property.

4680	   Conformance: The property can be specified once in the "VEVENT",
4681	   "VTODO" and "VJOURNAL" calendar components.

4683	   Description: The property value consists of the persistent, globally
4684	   unique identifier of another calendar component. This value would be
4685	   represented in a calendar component by the "UID" property.

4687	   By default, the property value points to another calendar component
4688	   that has a PARENT relationship to the referencing object. The
4689	   "RELTYPE" property parameter is used to either explicitly state the
4690	   default PARENT relationship type to the referenced calendar component
4691	   or to override the default PARENT relationship type and specify
4692	   either a CHILD or SIBLING relationship. The PARENT relationship
4693	   indicates that the calendar component is a subordinate of the
4694	   referenced calendar component. The CHILD relationship indicates that
4695	   the calendar component is a superior of the referenced calendar
4696	   component. The SIBLING relationship indicates that the calendar
4697	   component is a peer of the referenced calendar component.

4699	   Changes to a calendar component referenced by this property can have
4700	   an implicit impact on the related calendar component. For example, if
4701	   a group event changes its start or end date or time, then the
4702	   related, dependent events will need to have their start and end dates
4703	   changed in a corresponding way. Similarly, if a PARENT calendar
4704	   component is canceled or deleted, then there is an implied impact to
4705	   the related CHILD calendar components. This property is intended only
4706	   to provide information on the relationship of calendar components. It
4707	   is up to the target calendar system to maintain any property
4708	   implications of this relationship.

4710	   Format Definition: The property is defined by the following notation:

4712	     related    = "RELATED-TO" [relparam] ":" text CRLF

4714	     relparam   = [";" reltypeparam]
4715	                  *(";" xparm)

4717	   The following is an example of this property:

4719	     RELATED-TO:<jsmith.part7.19960817T083000.xyzMail@host3.com>

4721	     RELATED-TO:<19960401-080045-4000F192713-0052@host1.com>

4723	4.8.4.6 Uniform Resource Locator

4725	   Property Name: URL

4727	   Purpose: This property defines a Uniform Resource Locator (URL)
4728	   associated with the iCalendar object.

4730	   Value Type: URI

4732	   Property Parameters: Non-standard property parameters can be
4733	   specified on this property.

4735	   Conformance: This property can be specified once in the "VEVENT",
4736	   "VTODO", "VJOURNAL" and "VFREEBUSY" calendar components.

4738	   Description: This property may be used in a calendar component to
4739	   convey a location where a more dynamic rendition of the calendar
4740	   information associated with the calendar component can be found. This
4741	   memo does not attempt to standardize the form of the URI, nor the
4742	   format of the resource pointed to by the property value. If the URL
4743	   property and Content-Location MIME header are both specified, they
4744	   MUST point to the same resource.

4746	   Format Definition: The property is defined by the following notation:

4748	     url        = "URL" urlparam ":" uri CRLF

4750	     urlparam   = *(";" xparam)

4752	   Example: The following is an example of this property:

4754	     URL:http://abc.com/pub/calendars/jsmith/mytime.ics

4756	4.8.4.7 Unique Identifier

4758	   Property Name: UID

4760	   Purpose: This property defines the persistent, globally unique
4761	   identifier for the calendar component.

4763	   Value Type: TEXT

4765	   Property Parameters: Non-standard property parameters can be
4766	   specified on this property.

4768	   Conformance: The property MUST be specified in the "VEVENT", "VTODO",
4769	   "VJOURNAL" and "VFREEBUSY" calendar components.

4771	   Description: The UID itself MUST be a globally unique identifier. The
4772	   generator of the identifier MUST guarantee that the identifier is
4773	   unique. There are several algorithms that can be used to accomplish
4774	   this. The identifier is RECOMMENDED to be the identical syntax to the
4775	   [RFC 822] addr-spec. A good method to assure uniqueness is to put the
4776	   domain name or a domain literal IP address of the host on which the
4777	   identifier was created on the right hand side of the "@", and on the
4778	   left hand side, put a combination of the current calendar date and
4779	   time of day (i.e., formatted in as a DATE-TIME value) along with some
4780	   other currently unique (perhaps sequential) identifier available on
4781	   the system (for example, a process id number). Using a date/time
4782	   value on the left hand side and a domain name or domain literal on
4783	   the right hand side makes it possible to guarantee uniqueness since
4784	   no two hosts should be using the same domain name or IP address at
4785	   the same time. Though other algorithms will work, it is RECOMMENDED
4786	   that the right hand side contain some domain identifier (either of
4787	   the host itself or otherwise) such that the generator of the message
4788	   identifier can guarantee the uniqueness of the left hand side within
4789	   the scope of that domain.

4791	   This is the method for correlating scheduling messages with the
4792	   referenced "VEVENT", "VTODO", or "VJOURNAL" calendar component.

4794	   The full range of calendar components specified by a recurrence set
4795	   is referenced by referring to just the "UID" property value
4796	   corresponding to the calendar component. The "RECURRENCE-ID" property
4797	   allows the reference to an individual instance within the recurrence
4798	   set.

4800	   This property is an important method for group scheduling
4801	   applications to match requests with later replies, modifications or
4802	   deletion requests. Calendaring and scheduling applications MUST
4803	   generate this property in "VEVENT", "VTODO" and "VJOURNAL" calendar
4804	   components to assure interoperability with other group scheduling
4805	   applications. This identifier is created by the calendar system that
4806	   generates an iCalendar object.

4808	   Implementations MUST be able to receive and persist values of at
4809	   least 255 characters for this property.

4811	   Format Definition: The property is defined by the following notation:

4813	     uid        = "UID" uidparam ":" text CRLF

4815	     uidparam   = *(";" xparam)

4817	   Example: The following is an example of this property:

4819	     UID:19960401T080045Z-4000F192713-0052@host1.com

4821	4.8.5   Recurrence Component Properties

4823	   The following properties specify recurrence information in calendar
4824	   components.

4826	4.8.5.1 Exception Date/Times

4828	   Property Name: EXDATE

4830	   Purpose: This property defines the list of date/time exceptions for a
4831	   recurring calendar component.

4833	   Value Type: The default value type for this property is DATE-TIME.
4834	   The value type can be reset to DATE.

4836	   Property Parameters: Non-standard, value data type and time zone
4837	   identifier property parameters can be specified on this property.

4839	   Conformance: This property can be specified in an iCalendar object
4840	   that includes a recurring calendar component.

4842	   Description: The exception dates, if specified, is used in computing
4843	   the recurrence set. The recurrence set is the complete set of
4844	   recurrence instances for a calendar component. The recurrence set is
4845	   generated by considering the initial "DTSTART" property along with
4846	   the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
4847	   within the iCalendar object. The "DTSTART" property defines the first
4848	   instance in the recurrence set. Multiple instances of the "RRULE" and
4849	   "EXRULE" properties can also be specified to define more
4850	   sophisticated recurrence sets. The final recurrence set is generated
4851	   by gathering all of the start date-times generated by any of the
4852	   specified "RRULE" and "RDATE" properties, and then excluding any
4853	   start date and times which fall within the union of start date and
4854	   times generated by any specified "EXRULE" and "EXDATE" properties.
4855	   This implies that start date and times within exclusion related
4856	   properties (i.e., "EXDATE" and "EXRULE") take precedence over those
4857	   specified by inclusion properties (i.e., "RDATE" and "RRULE"). Where
4858	   duplicate instances are generated by the "RRULE" and "RDATE"
4859	   properties, only one recurrence is considered. Duplicate instances
4860	   are ignored.

4862	   The "EXDATE" property can be used to exclude the value specified in
4863	   "DTSTART". However, in such cases the original "DTSTART" date MUST
4864	   still be maintained by the calendaring and scheduling system because
4865	   the original "DTSTART" value has inherent usage dependencies by other
4866	   properties such as the "RECURRENCE-ID".

4868	   Format Definition: The property is defined by the following notation:

4870	     exdate     = "EXDATE" exdtparam ":" exdtval *("," exdtval) CRLF

4872	     exdtparam  = [";" "VALUE" "=" ("DATE-TIME" / "DATE")]
4873	                  [";" tzidparam]
4874	                  *(";" xparam)

4876	     exdtval    = date-time / date
4877	     ;Value MUST match value type

4879	   Example: The following is an example of this property:

4881	     EXDATE:19960402T010000Z,19960403T010000Z,19960404T010000Z

4883	4.8.5.2 Exception Rule

4885	   Property Name: EXRULE

4887	   Purpose: This property defines a rule or repeating pattern for an
4888	   exception to a recurrence set.

4890	   Value Type: RECUR
4891	   Property Parameters: Non-standard property parameters can be
4892	   specified on this property.

4894	   Conformance: This property can be specified in the "VEVENT", "VTODO"
4895	   or "VJOURNAL" calendar components.

4897	   Description: The exception rule, if specified, is used in computing
4898	   the recurrence set. The recurrence set is the complete set of
4899	   recurrence instances for a calendar component. The recurrence set is
4900	   generated by considering the initial "DTSTART" property along with
4901	   the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
4902	   within the iCalendar object. The "DTSTART" defines the first instance
4903	   in the recurrence set. Multiple instances of the "RRULE" and "EXRULE"
4904	   properties can also be specified to define more sophisticated
4905	   recurrence sets. The final recurrence set is generated by gathering
4906	   all of the start date-times generated by any of the specified "RRULE"
4907	   and "RDATE" properties, and excluding any start date and times which
4908	   fall within the union of start date and times generated by any
4909	   specified "EXRULE" and "EXDATE" properties. This implies that start
4910	   date and times within exclusion related properties (i.e., "EXDATE"
4911	   and "EXRULE") take precedence over those specified by inclusion
4912	   properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
4913	   generated by the "RRULE" and "RDATE" properties, only one recurrence
4914	   is considered. Duplicate instances are ignored.

4916	   The "EXRULE" property can be used to exclude the value specified in
4917	   "DTSTART". However, in such cases the original "DTSTART" date MUST
4918	   still be maintained by the calendaring and scheduling system because
4919	   the original "DTSTART" value has inherent usage dependencies by other
4920	   properties such as the "RECURRENCE-ID".

4922	   Format Definition: The property is defined by the following notation:

4924	     exrule     = "EXRULE" exrparam ":" recur CRLF

4926	     exrparam   = *(";" xparam)

4928	   Example: The following are examples of this property. Except every
4929	   other week, on Tuesday and Thursday for 4 occurrences:

4931	     EXRULE:FREQ=WEEKLY;COUNT=4;INTERVAL=2;BYDAY=TU,TH

4933	   Except daily for 10 occurrences:

4935	     EXRULE:FREQ=DAILY;COUNT=10

4937	   Except yearly in June and July for 8 occurrences:

4939	     EXRULE:FREQ=YEARLY;COUNT=8;BYMONTH=6,7

4941	4.8.5.3 Recurrence Date/Times

4943	   Property Name: RDATE
4944	   Purpose: This property defines the list of date/times for a
4945	   recurrence set.

4947	   Value Type: The default value type for this property is DATE-TIME.
4948	   The value type can be reset to DATE or PERIOD.

4950	   Property Parameters: Non-standard, value data type and time zone
4951	   identifier property parameters can be specified on this property.

4953	   Conformance: The property can appear within the "VEVENT", "VTODO",
4954	   "VJOURNAL" and "VTIMEZONE" calendar components.

4956	   Description: This property can appear along with the "RRULE" property
4957	   to define an aggregate set of repeating occurrences. When they both
4958	   appear in an iCalendar object, the recurring events are defined by
4959	   the union of occurrences defined by both the "RDATE" and "RRULE".

4961	   The recurrence dates, if specified, is used in computing the
4962	   recurrence set. The recurrence set is the complete set of recurrence
4963	   instances for a calendar component. The recurrence set is generated
4964	   by considering the initial "DTSTART" property along with the "RRULE",
4965	   "RDATE", "EXDATE" and "EXRULE" properties contained within the
4966	   iCalendar object. The "DTSTART" property defines the first instance
4967	   in the recurrence set. Multiple instances of the "RRULE" and "EXRULE"
4968	   properties can also be specified to define more sophisticated
4969	   recurrence sets. The final recurrence set is generated by gathering
4970	   all of the start date-times generated by any of the specified "RRULE"
4971	   and "RDATE" properties, and excluding any start date and times which
4972	   fall within the union of start date and times generated by any
4973	   specified "EXRULE" and "EXDATE" properties. This implies that start
4974	   date and times within exclusion related properties (i.e., "EXDATE"
4975	   and "EXRULE") take precedence over those specified by inclusion
4976	   properties (i.e., "RDATE" and "RRULE"). Where duplicate instances are
4977	   generated by the "RRULE" and "RDATE" properties, only one recurrence
4978	   is considered. Duplicate instances are ignored.

4980	   Format Definition: The property is defined by the following notation:

4982	     rdate      = "RDATE" rdtparam ":" rdtval *("," rdtval) CRLF

4984	     rdtparam   = [";" "VALUE" "=" ("DATE-TIME" / "DATE"
4985	                  / "PERIOD")]
4986	                  [";" tzidparam]
4987	                  *(";" xparam)

4989	     rdtval     = date-time / date / period
4990	     ;Value MUST match value type

4992	   Example: The following are examples of this property:

4994	     RDATE:19970714T123000Z

4996	     RDATE;TZID=US-EASTERN:19970714T083000
4997	     RDATE;VALUE=PERIOD:19960403T020000Z/19960403T040000Z,
4998	      19960404T010000Z/PT3H

5000	     RDATE;VALUE=DATE:19970101,19970120,19970217,19970421
5001	      19970526,19970704,19970901,19971014,19971128,19971129,19971225

5003	4.8.5.4 Recurrence Rule

5005	   Property Name: RRULE

5007	   Purpose: This property defines a rule or repeating pattern for
5008	   recurring events, to-dos, or time zone definitions.

5010	   Value Type: RECUR

5012	   Property Parameters: Non-standard property parameters can be
5013	   specified on this property.

5015	   Conformance: This property can be specified one or more times in
5016	   recurring "VEVENT", "VTODO" and "VJOURNAL" calendar components. It
5017	   can also be specified once in each STANDARD or DAYLIGHT sub-component
5018	   of the "VTIMEZONE" calendar component.

5020	   Description: The recurring rule, if specified, is used in computing
5021	   the recurrence set. The recurrence set is the complete set of
5022	   recurrence instances for a calendar component. The recurrence set is
5023	   generated by considering the initial "DTSTART" property along with
5024	   the "RRULE", "RDATE", "EXDATE" and "EXRULE" properties contained
5025	   within the iCalendar object. The "DTSTART" property defines the first
5026	   instance in the recurrence set. Multiple instances of the "RRULE" and
5027	   "EXRULE" properties can also be specified to define more
5028	   sophisticated recurrence sets. The final recurrence set is generated
5029	   by gathering all of the start date-times generated by any of the
5030	   specified "RRULE" and "RDATE" properties, and excluding any start
5031	   date and times which fall within the union of start date and times
5032	   generated by any specified "EXRULE" and "EXDATE" properties. This
5033	   implies that start date and times within exclusion related properties
5034	   (i.e., "EXDATE" and "EXRULE") take precedence over those specified by
5035	   inclusion properties (i.e., "RDATE" and "RRULE"). Where duplicate
5036	   instances are generated by the "RRULE" and "RDATE" properties, only
5037	   one recurrence is considered. Duplicate instances are ignored.

5039	   The "DTSTART" and "DTEND" property pair or "DTSTART" and "DURATION"
5040	   property pair, specified within the iCalendar object defines the
5041	   first instance of the recurrence. When used with a recurrence rule,
5042	   the "DTSTART" and "DTEND" properties MUST be specified in local time
5043	   and the appropriate set of "VTIMEZONE" calendar components MUST be
5044	   included. For detail on the usage of the "VTIMEZONE" calendar
5045	   component, see the "VTIMEZONE" calendar component definition.

5047	   Any duration associated with the iCalendar object applies to all
5048	   members of the generated recurrence. Any modified duration for
5049	   specific recurrences would have to be explicitly specified using the
5050	   "RDATE" property.

5052	   Format Definition: This property is defined by the following
5053	   notation:

5055	     rrule      = "RRULE" rrulparam ":" recur CRLF

5057	     rrulparam  = *(";" xparam)

5059	   Example: All examples assume the Eastern United States time zone.

5061	   Daily for 10 occurrences:

5063	     DTSTART;TZID=America-New York:19970902T090000
5064	     RRULE:FREQ=DAILY;COUNT=10

5066	     ==> (1997 9:00 AM EDT)September 2-11

5068	   Daily until December 24, 1997:

5070	     DTSTART;TZID=America-New York:19970902T090000
5071	     RRULE:FREQ=DAILY;UNTIL=19971224T000000Z

5073	     ==> (1997 9:00 AM EDT)September 2-30;October 1-25
5074	         (1997 9:00 AM EST)October 26-31;November 1-30;December 1-23

5076	   Every other day - forever:

5078	     DTSTART;TZID=America-New York:19970902T090000
5079	     RRULE:FREQ=DAILY;INTERVAL=2
5080	     ==> (1997 9:00 AM EDT)September2,4,6,8...24,26,28,30;
5081	          October 2,4,6...20,22,24
5082	         (1997 9:00 AM EST)October 26,28,30;November 1,3,5,7...25,27,29;
5083	          Dec 1,3,...

5085	   Every 10 days, 5 occurrences:

5087	     DTSTART;TZID=America-New York:19970902T090000
5088	     RRULE:FREQ=DAILY;INTERVAL=10;COUNT=5

5090	     ==> (1997 9:00 AM EDT)September 2,12,22;October 2,12

5092	   Everyday in January, for 3 years:

5094	     DTSTART;TZID=America-New York:19980101T090000
5095	     RRULE:FREQ=YEARLY;UNTIL=20000131T090000Z;
5096	      BYMONTH=1;BYDAY=SU,MO,TU,WE,TH,FR,SA
5097	     or
5098	     RRULE:FREQ=DAILY;UNTIL=20000131T090000Z;BYMONTH=1

5100	     ==> (1998 9:00 AM EDT)January 1-31
5101	         (1999 9:00 AM EDT)January 1-31
5102	         (2000 9:00 AM EDT)January 1-31

5104	   Weekly for 10 occurrences
5105	     DTSTART;TZID=America-New York:19970902T090000
5106	     RRULE:FREQ=WEEKLY;COUNT=10

5108	     ==> (1997 9:00 AM EDT)September 2,9,16,23,30;October 7,14,21
5109	         (1997 9:00 AM EST)October 28;November 4

5111	   Weekly until December 24, 1997

5113	     DTSTART;TZID=America-New York:19970902T090000
5114	     RRULE:FREQ=WEEKLY;UNTIL=19971224T000000Z

5116	     ==> (1997 9:00 AM EDT)September 2,9,16,23,30;October 7,14,21
5117	         (1997 9:00 AM EST)October 28;November 4,11,18,25;
5118	                       December 2,9,16,23

5120	   Every other week - forever:

5122	     DTSTART;TZID=America-New York:19970902T090000
5123	     RRULE:FREQ=WEEKLY;INTERVAL=2;WKST=SU

5125	     ==> (1997 9:00 AM EDT)September 2,16,30;October 14
5126	         (1997 9:00 AM EST)October 28;November 11,25;December 9,23
5127	         (1998 9:00 AM EST)January 6,20;February
5128	     ...

5130	   Weekly on Tuesday and Thursday for 5 weeks:

5132	     DTSTART;TZID=America-New York:19970902T090000
5133	     RRULE:FREQ=WEEKLY;UNTIL=19971007T000000Z;WKST=SU;BYDAY=TU,TH
5134	     or
5135	     RRULE:FREQ=WEEKLY;COUNT=10;WKST=SU;BYDAY=TU,TH

5137	     ==> (1997 9:00 AM EDT)September 2,4,9,11,16,18,23,25,30;October 2

5139	   Every other week on Monday, Wednesday and Friday until December 24,
5140	   1997, but starting on Tuesday, September 2, 1997:

5142	     DTSTART;TZID=America-New York:19970902T090000
5143	     RRULE:FREQ=WEEKLY;INTERVAL=2;UNTIL=19971224T000000Z;WKST=SU;
5144	      BYDAY=MO,WE,FR
5145	     ==> (1997 9:00 AM EDT)September 2,3,5,15,17,19,29;October
5146	     1,3,13,15,17
5147	         (1997 9:00 AM EST)October 27,29,31;November 10,12,14,24,26,28;
5148	                           December 8,10,12,22

5150	   Every other week on Tuesday and Thursday, for 8 occurrences:

5152	     DTSTART;TZID=America-New York:19970902T090000
5153	     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH

5155	     ==> (1997 9:00 AM EDT)September 2,4,16,18,30;October 2,14,16

5157	   Monthly on the 1st Friday for ten occurrences:

5159	     DTSTART;TZID=America-New York:19970905T090000
5160	     RRULE:FREQ=MONTHLY;COUNT=10;BYDAY=1FR

5162	     ==> (1997 9:00 AM EDT)September 5;October 3
5163	         (1997 9:00 AM EST)November 7;Dec 5
5164	         (1998 9:00 AM EST)January 2;February 6;March 6;April 3
5165	         (1998 9:00 AM EDT)May 1;June 5

5167	   Monthly on the 1st Friday until December 24, 1997:

5169	     DTSTART;TZID=America-New York:19970905T090000
5170	     RRULE:FREQ=MONTHLY;UNTIL=19971224T000000Z;BYDAY=1FR

5172	     ==> (1997 9:00 AM EDT)September 5;October 3
5173	         (1997 9:00 AM EST)November 7;December 5

5175	   Every other month on the 1st and last Sunday of the month for 10
5176	   occurrences:

5178	     DTSTART;TZID=America-New York:19970907T090000
5179	     RRULE:FREQ=MONTHLY;INTERVAL=2;COUNT=10;BYDAY=1SU,-1SU

5181	     ==> (1997 9:00 AM EDT)September 7,28
5182	         (1997 9:00 AM EST)November 2,30
5183	         (1998 9:00 AM EST)January 4,25;March 1,29
5184	         (1998 9:00 AM EDT)May 3,31

5186	   Monthly on the second to last Monday of the month for 6 months:

5188	     DTSTART;TZID=America-New York:19970922T090000
5189	     RRULE:FREQ=MONTHLY;COUNT=6;BYDAY=-2MO

5191	     ==> (1997 9:00 AM EDT)September 22;October 20
5192	         (1997 9:00 AM EST)November 17;December 22
5193	         (1998 9:00 AM EST)January 19;February 16

5195	   Monthly on the third to the last day of the month, forever:

5197	     DTSTART;TZID=America-New York:19970928T090000
5198	     RRULE:FREQ=MONTHLY;BYMONTHDAY=-3

5200	     ==> (1997 9:00 AM EDT)September 28
5201	         (1997 9:00 AM EST)October 29;November 28;December 29
5202	         (1998 9:00 AM EST)January 29;February 26
5203	     ...

5205	   Monthly on the 2nd and 15th of the month for 10 occurrences:

5207	     DTSTART;TZID=America-New York:19970902T090000
5208	     RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=2,15

5210	     ==> (1997 9:00 AM EDT)September 2,15;October 2,15
5211	         (1997 9:00 AM EST)November 2,15;December 2,15
5212	         (1998 9:00 AM EST)January 2,15
5213	   Monthly on the first and last day of the month for 10 occurrences:

5215	     DTSTART;TZID=America-New York:19970930T090000
5216	     RRULE:FREQ=MONTHLY;COUNT=10;BYMONTHDAY=1,-1

5218	     ==> (1997 9:00 AM EDT)September 30;October 1
5219	         (1997 9:00 AM EST)October 31;November 1,30;December 1,31
5220	         (1998 9:00 AM EST)January 1,31;February 1

5222	   Every 18 months on the 10th thru 15th of the month for 10
5223	   occurrences:

5225	     DTSTART;TZID=America-New York:19970910T090000
5226	     RRULE:FREQ=MONTHLY;INTERVAL=18;COUNT=10;BYMONTHDAY=10,11,12,13,14,
5227	      15

5229	     ==> (1997 9:00 AM EDT)September 10,11,12,13,14,15
5230	         (1999 9:00 AM EST)March 10,11,12,13

5232	   Every Tuesday, every other month:

5234	     DTSTART;TZID=America-New York:19970902T090000
5235	     RRULE:FREQ=MONTHLY;INTERVAL=2;BYDAY=TU

5237	     ==> (1997 9:00 AM EDT)September 2,9,16,23,30
5238	         (1997 9:00 AM EST)November 4,11,18,25
5239	         (1998 9:00 AM EST)January 6,13,20,27;March 3,10,17,24,31
5240	     ...

5242	   Yearly in June and July for 10 occurrences:

5244	     DTSTART;TZID=America-New York:19970610T090000
5245	     RRULE:FREQ=YEARLY;COUNT=10;BYMONTH=6,7

5247	     ==> (1997 9:00 AM EDT)June 10;July 10
5248	         (1998 9:00 AM EDT)June 10;July 10
5249	         (1999 9:00 AM EDT)June 10;July 10
5250	         (2000 9:00 AM EDT)June 10;July 10
5251	         (2001 9:00 AM EDT)June 10;July 10
5252	     Note: Since none of the BYDAY, BYMONTHDAY or BYYEARDAY components
5253	     are specified, the day is gotten from DTSTART

5255	   Every other year on January, February, and March for 10 occurrences:

5257	     DTSTART;TZID=America-New York:19970310T090000
5258	     RRULE:FREQ=YEARLY;INTERVAL=2;COUNT=10;BYMONTH=1,2,3

5260	     ==> (1997 9:00 AM EST)March 10
5261	         (1999 9:00 AM EST)January 10;February 10;March 10
5262	         (2001 9:00 AM EST)January 10;February 10;March 10
5263	         (2003 9:00 AM EST)January 10;February 10;March 10

5265	   Every 3rd year on the 1st, 100th and 200th day for 10 occurrences:

5267	     DTSTART;TZID=America-New York:19970101T090000
5268	     RRULE:FREQ=YEARLY;INTERVAL=3;COUNT=10;BYYEARDAY=1,100,200

5270	     ==> (1997 9:00 AM EST)January 1
5271	         (1997 9:00 AM EDT)April 10;July 19
5272	         (2000 9:00 AM EST)January 1
5273	         (2000 9:00 AM EDT)April 9;July 18
5274	         (2003 9:00 AM EST)January 1
5275	         (2003 9:00 AM EDT)April 10;July 19
5276	         (2006 9:00 AM EST)January 1

5278	   Every 20th Monday of the year, forever:

5280	     DTSTART;TZID=America-New York:19970519T090000
5281	     RRULE:FREQ=YEARLY;BYDAY=20MO

5283	     ==> (1997 9:00 AM EDT)May 19
5284	         (1998 9:00 AM EDT)May 18
5285	         (1999 9:00 AM EDT)May 17
5286	     ...

5288	   Monday of week number 20 (where the default start of the week is
5289	   Monday), forever:

5291	     DTSTART;TZID=America-New York:19970512T090000
5292	     RRULE:FREQ=YEARLY;BYWEEKNO=20;BYDAY=MO

5294	     ==> (1997 9:00 AM EDT)May 12
5295	         (1998 9:00 AM EDT)May 11
5296	         (1999 9:00 AM EDT)May 17
5297	     ...

5299	   Every Thursday in March, forever:

5301	     DTSTART;TZID=America-New York:19970313T090000
5302	     RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=TH

5304	     ==> (1997 9:00 AM EST)March 13,20,27
5305	         (1998 9:00 AM EST)March 5,12,19,26
5306	         (1999 9:00 AM EST)March 4,11,18,25
5307	     ...

5309	   Every Thursday, but only during June, July, and August, forever:

5311	     DTSTART;TZID=America-New York:19970605T090000
5312	     RRULE:FREQ=YEARLY;BYDAY=TH;BYMONTH=6,7,8

5314	     ==> (1997 9:00 AM EDT)June 5,12,19,26;July 3,10,17,24,31;
5315	                       August 7,14,21,28
5316	         (1998 9:00 AM EDT)June 4,11,18,25;July 2,9,16,23,30;
5317	                       August 6,13,20,27
5318	         (1999 9:00 AM EDT)June 3,10,17,24;July 1,8,15,22,29;
5319	                       August 5,12,19,26
5320	     ...

5322	   Every Friday the 13th, forever:

5324	     DTSTART;TZID=America-New York:19970902T090000
5325	     EXDATE;TZID=America-New York:19970902T090000
5326	     RRULE:FREQ=MONTHLY;BYDAY=FR;BYMONTHDAY=13

5328	     ==> (1998 9:00 AM EST)February 13;March 13;November 13
5329	         (1999 9:00 AM EDT)August 13
5330	         (2000 9:00 AM EDT)October 13
5331	     ...

5333	   The first Saturday that follows the first Sunday of the month,
5334	   forever:

5336	     DTSTART;TZID=America-New York:19970913T090000
5337	     RRULE:FREQ=MONTHLY;BYDAY=SA;BYMONTHDAY=7,8,9,10,11,12,13

5339	     ==> (1997 9:00 AM EDT)September 13;October 11
5340	         (1997 9:00 AM EST)November 8;December 13
5341	         (1998 9:00 AM EST)January 10;February 7;March 7
5342	         (1998 9:00 AM EDT)April 11;May 9;June 13...
5343	     ...

5345	   Every four years, the first Tuesday after a Monday in November,
5346	   forever (U.S. Presidential Election day):

5348	     DTSTART;TZID=America-New York:19961105T090000
5349	     RRULE:FREQ=YEARLY;INTERVAL=4;BYMONTH=11;BYDAY=TU;BYMONTHDAY=2,3,4,
5350	      5,6,7,8

5352	     ==> (1996 9:00 AM EST)November 5
5353	         (2000 9:00 AM EST)November 7
5354	         (2004 9:00 AM EST)November 2
5355	     ...

5357	   The 3rd instance into the month of one of Tuesday, Wednesday or
5358	   Thursday, for the next 3 months:

5360	     DTSTART;TZID=America-New York:19970904T090000
5361	     RRULE:FREQ=MONTHLY;COUNT=3;BYDAY=TU,WE,TH;BYSETPOS=3

5363	     ==> (1997 9:00 AM EDT)September 4;October 7
5364	         (1997 9:00 AM EST)November 6

5366	   The 2nd to last weekday of the month:

5368	     DTSTART;TZID=America-New York:19970929T090000
5369	     RRULE:FREQ=MONTHLY;BYDAY=MO,TU,WE,TH,FR;BYSETPOS=-2

5371	     ==> (1997 9:00 AM EDT)September 29
5372	         (1997 9:00 AM EST)October 30;November 27;December 30
5373	         (1998 9:00 AM EST)January 29;February 26;March 30
5374	     ...

5376	   Every 3 hours from 9:00 AM to 5:00 PM on a specific day:

5378	     DTSTART;TZID=America-New York:19970902T090000
5379	     RRULE:FREQ=HOURLY;INTERVAL=3;UNTIL=19970902T170000Z

5381	     ==> (September 2, 1997 EDT)09:00,12:00,15:00

5383	   Every 15 minutes for 6 occurrences:

5385	     DTSTART;TZID=America-New York:19970902T090000
5386	     RRULE:FREQ=MINUTELY;INTERVAL=15;COUNT=6

5388	     ==> (September 2, 1997 EDT)09:00,09:15,09:30,09:45,10:00,10:15

5390	   Every hour and a half for 4 occurrences:

5392	     DTSTART;TZID=America-New York:19970902T090000
5393	     RRULE:FREQ=MINUTELY;INTERVAL=90;COUNT=4

5395	     ==> (September 2, 1997 EDT)09:00,10:30;12:00;13:30

5397	   Every 20 minutes from 9:00 AM to 4:40 PM every day:

5399	     DTSTART;TZID=America-New York:19970902T090000
5400	     RRULE:FREQ=DAILY;BYHOUR=9,10,11,12,13,14,15,16;BYMINUTE=0,20,40
5401	     or
5402	     RRULE:FREQ=MINUTELY;INTERVAL=20;BYHOUR=9,10,11,12,13,14,15,16

5404	     ==> (September 2, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
5405	                                ... 16:00,16:20,16:40
5406	         (September 3, 1997 EDT)9:00,9:20,9:40,10:00,10:20,
5407	                               ...16:00,16:20,16:40
5408	     ...

5410	   An example where the days generated makes a difference because of
5411	   WKST:

5413	     DTSTART;TZID=America-New York:19970805T090000
5414	     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=MO

5416	     ==> (1997 EDT)Aug 5,10,19,24

5418	     changing only WKST from MO to SU, yields different results...

5420	     DTSTART;TZID=America-New York:19970805T090000
5421	     RRULE:FREQ=WEEKLY;INTERVAL=2;COUNT=4;BYDAY=TU,SU;WKST=SU
5422	     ==> (1997 EDT)August 5,17,19,31

5424	4.8.6   Alarm Component Properties

5426	   The following properties specify alarm information in calendar
5427	   components.

5429	4.8.6.1 Action

5431	   Property Name: ACTION

5433	   Purpose: This property defines the action to be invoked when an alarm
5434	   is triggered.

5436	   Value Type: TEXT

5438	   Property Parameters: Non-standard property parameters can be
5439	   specified on this property.

5441	   Conformance: This property MUST be specified once within a "VALARM"
5442	   calendar component.

5444	   Description: Each "VALARM" calendar component has a particular type
5445	   of action associated with it. This property specifies the type of
5446	   action

5448	   Format Definition: The property is defined by the following notation:

5450	     action     = "ACTION" actionparam ":" actionvalue CRLF

5452	     actionparam        = *(";" xparam)

5454	     actionvalue        = "AUDIO" / "DISPLAY" / "EMAIL" / "PROCEDURE"
5455	                        / iana-token / x-name

5457	   Example: The following are examples of this property in a "VALARM"
5458	   calendar component:

5460	     ACTION:AUDIO

5462	     ACTION:DISPLAY

5464	     ACTION:PROCEDURE

5466	4.8.6.2 Repeat Count

5468	   Property Name: REPEAT

5470	   Purpose: This property defines the number of time the alarm should be
5471	   repeated, after the initial trigger.

5473	   Value Type: INTEGER

5475	   Property Parameters: Non-standard property parameters can be
5476	   specified on this property.

5478	   Conformance: This property can be specified in a "VALARM" calendar
5479	   component.

5481	   Description: If the alarm triggers more than once, then this property
5482	   MUST be specified along with the "DURATION" property.

5484	   Format Definition: The property is defined by the following notation:

5486	     repeatcnt  = "REPEAT" repparam ":" integer CRLF
5487	     ;Default is "0", zero.

5489	     repparam   = *(";" xparam)

5491	   Example: The following is an example of this property for an alarm
5492	   that repeats 4 additional times with a 5 minute delay after the
5493	   initial triggering of the alarm.:

5495	     REPEAT:4
5496	     DURATION:PT5M

5498	4.8.6.3 Trigger

5500	   Property Name: TRIGGER

5502	   Purpose: This property specifies when an alarm will trigger.

5504	   Value Type: The default value type is DURATION. The value type can be
5505	   reset to a DATE-TIME value type, in which case the value MUST specify
5506	   a UTC formatted DATE-TIME value.

5508	   Property Parameters: Non-standard, value data type, time zone
5509	   identifier or trigger relationship property parameters can be
5510	   specified on this property. The trigger relationship property
5511	   parameter MUST only be specified when the value type is DURATION.

5513	   Conformance: This property MUST be specified within the "VALARM"
5514	   calendar component.

5516	   Description: Within the "VALARM" calendar component, this property
5517	   defines when the alarm will trigger. The default value type is
5518	   DURATION, specifying a relative time for the trigger of the alarm.
5519	   The default duration is relative to the start of an event or to-do
5520	   that the alarm is associated with. The duration can be explicitly set
5521	   to trigger from either the end or the start of the associated event
5522	   or to-do with the "RELATED" parameter. A value of START will set the
5523	   alarm to trigger off the start of the associated event or to-do. A
5524	   value of END will set the alarm to trigger off the end of the
5525	   associated event or to-do.

5527	   Either a positive or negative duration may be specified for the
5528	   "TRIGGER" property. An alarm with a positive duration is triggered
5529	   after the associated start or end of the event or to-do. An alarm
5530	   with a negative duration is triggered before the associated start or
5531	   end of the event or to-do.

5533	   The "RELATED" property parameter is not valid if the value type of
5534	   the property is reset to DATE-TIME (i.e., for an absolute date and
5535	   time alarm trigger). If a value type of DATE-TIME is specified, then
5536	   the property value MUST be specified in the UTC time format. If an
5537	   absolute trigger is specified on an alarm for a recurring event or
5538	   to-do, then the alarm will only trigger for the specified absolute
5539	   date/time, along with any specified repeating instances.

5541	   If the trigger is set relative to START, then the "DTSTART" property
5542	   must be present in the associated "VEVENT" or "VTODO" calendar
5543	   component. If an alarm is specified for an event with the trigger set
5544	   relative to the END, then the "DTEND" property or the "DSTART" and
5545	   "DURATION' properties must be present in the associated "VEVENT"
5546	   calendar component. If the alarm is specified for a to-do with a
5547	   trigger set relative to the END, then either the "DUE" property or
5548	   the "DSTART" and "DURATION' properties must be present in the
5549	   associated "VTODO" calendar component.

5551	   Alarms specified in an event or to-do which is defined in terms of a
5552	   DATE value type will be triggered relative to 00:00:00 UTC on the
5553	   specified date. For example, if "DTSTART:19980205, then the duration
5554	   trigger will be relative to19980205T000000Z.

5556	   Format Definition: The property is defined by the following notation:

5558	     trigger    = "TRIGGER" (trigrel / trigabs)

5560	     trigrel    = [";" "VALUE" "=" "DURATION"]
5561	                   [";" trigrelparam] *(";" xparam)
5562	                  ":"  duration

5564	     trigabs    = ";" "VALUE" "=" "DATE-TIME" *(";" xparam)
5565	                  ":" date-time

5567	   Example: A trigger set 15 minutes prior to the start of the event or
5568	   to-do.

5570	     TRIGGER:-P15M

5572	   A trigger set 5 minutes after the end of the event or to-do.

5574	     TRIGGER;RELATED=END:P5M

5576	   A trigger set to an absolute date/time.

5578	     TRIGGER;VALUE=DATE-TIME:19980101T050000Z

5580	4.8.7   Change Management Component Properties

5582	   The following properties specify change management information in
5583	   calendar components.

5585	4.8.7.1 Date/Time Created

5587	   Property Name: CREATED

5589	   Purpose: This property specifies the date and time that the calendar
5590	   information was created by the calendar user agent in the calendar
5591	   store.

5593	        Note: This is analogous to the creation date and time for a file
5594	        in the file system.

5596	   Value Type: DATE-TIME

5598	   Property Parameters: Non-standard property parameters can be
5599	   specified on this property.

5601	   Conformance: The property can be specified once in "VEVENT", "VTODO"
5602	   and "VJOURNAL" calendar components.

5604	   Description: The date and time is an UTC value.

5606	   Format Definition: The property is defined by the following notation:

5608	     created    = "CREATED" creaparam ":" date-time CRLF

5610	     creaparam  = *(";" xparam)

5612	   Example: The following is an example of this property:

5614	     CREATED:19960329T133000Z

5616	4.8.7.2 Date/Time Stamp

5618	   Property Name: DTSTAMP

5620	   Purpose: The property indicates the date/time that the instance of
5621	   the iCalendar object was created.

5623	   Value Type: DATE-TIME

5625	   Property Parameters: Non-standard property parameters can be
5626	   specified on this property.

5628	   Conformance: This property MUST be included in the "VEVENT", "VTODO",
5629	   "VJOURNAL" and "VFREEBUSY" calendar components.

5631	   Description: The value must be specified in the UTC time format.

5633	   This property is also useful to protocols such as [IMIP] that have
5634	   inherent latency issues with the delivery of content. This property
5635	   will assist in the proper sequencing of messages containing iCalendar
5636	   objects.

5638	   This property is different than the "CREATED" and "LAST-MODIFIED"
5639	   properties. These two properties are used to specify when the
5640	   calendar service information was created and last modified. This is
5641	   different than when the iCalendar object representation of the
5642	   calendar service information was created or last modified.

5644	   Format Definition: The property is defined by the following notation:

5646	     dtstamp    = "DTSTAMP" stmparam ":" date-time CRLF
5647	     stmparam   = *(";" xparam)

5649	   Example:

5651	     DTSTAMP:19971210T080000Z

5653	4.8.7.3 Last Modified

5655	   Property Name: LAST-MODIFIED

5657	   Purpose: The property specifies the date and time that the
5658	   information associated with the calendar component was last revised
5659	   in the calendar store.

5661	        Note: This is analogous to the modification date and time for a
5662	        file in the file system.

5664	   Value Type: DATE-TIME

5666	   Property Parameters: Non-standard property parameters can be
5667	   specified on this property.

5669	   Conformance: This property can be specified in the "EVENT", "VTODO",
5670	   "VJOURNAL" and "VTIMEZONE" calendar components.

5672	   Description: The property value MUST be specified in the UTC time
5673	   format.

5675	   Format Definition: The property is defined by the following notation:

5677	     last-mod   = "LAST-MODIFIED" lstparam ":" date-time CRLF

5679	     lstparam   = *(";" xparam)

5681	   Example: The following is are examples of this property:

5683	     LAST-MODIFIED:19960817T133000Z

5685	4.8.7.4 Sequence Number

5687	   Property Name: SEQUENCE

5689	   Purpose: This property defines the revision sequence number of the
5690	   calendar component within a sequence of revisions.

5692	   Value Type: integer

5694	   Property Parameters: Non-standard property parameters can be
5695	   specified on this property.

5697	   Conformance: The property can be specified in a "VEVENT", "VTODO",
5698	   "VJOURNAL" calendar component.

5700	   Description: When a calendar component is created, its sequence
5701	   number is zero (US-ASCII decimal 48). It is monotonically incremented
5702	   by the "Organizer's" CUA each time the "Organizer" makes a
5703	   significant revision to the calendar component. When the "Organizer"
5704	   makes changes to one of the following properties, the sequence number
5705	   MUST be incremented:

5707	     .  "DTSTART"

5709	     .  "DTEND"

5711	     .  "DUE"

5713	     .  "RDATE"

5715	     .  "RRULE"

5717	     .  "EXDATE"

5719	     .  "EXRULE"

5721	     .  "STATUS"

5723	   In addition, changes made by the "Organizer" to other properties can
5724	   also force the sequence number to be incremented. The "Organizer" CUA
5725	   MUST increment the sequence number when ever it makes changes to
5726	   properties in the calendar component that the "Organizer" deems will
5727	   jeopardize the validity of the participation status of the
5728	   "Attendees". For example, changing the location of a meeting from one
5729	   locale to another distant locale could effectively impact the
5730	   participation status of the "Attendees".

5732	   The "Organizer" includes this property in an iCalendar object that it
5733	   sends to an "Attendee" to specify the current version of the calendar
5734	   component.

5736	   The "Attendee" includes this property in an iCalendar object that it
5737	   sends to the "Organizer" to specify the version of the calendar
5738	   component that the "Attendee" is referring to.

5740	   A change to the sequence number is not the mechanism that an
5741	   "Organizer" uses to request a response from the "Attendees". The
5742	   "RSVP" parameter on the "ATTENDEE" property is used by the
5743	   "Organizer" to indicate that a response from the "Attendees" is
5744	   requested.

5746	   Format Definition: This property is defined by the following
5747	   notation:

5749	     seq = "SEQUENCE" seqparam ":" integer CRLF
5750	     ; Default is "0"

5752	     seqparam   = *(";" xparam)
5753	   Example: The following is an example of this property for a calendar
5754	   component that was just created by the "Organizer".

5756	     SEQUENCE:0

5758	   The following is an example of this property for a calendar component
5759	   that has been revised two different times by the "Organizer".

5761	     SEQUENCE:2

5763	4.8.8   Miscellaneous Component Properties

5765	   The following properties specify information about a number of
5766	   miscellaneous features of calendar components.

5768	4.8.8.1 Non-standard Properties

5770	   Property Name: Any property name with a "X-" prefix

5772	   Purpose: This class of property provides a framework for defining
5773	   non-standard properties.

5775	   Value Type: TEXT

5777	   Property Parameters: Non-standard and language property parameters
5778	   can be specified on this property.

5780	   Conformance: This property can be specified in any calendar
5781	   component.

5783	   Description: The MIME Calendaring and Scheduling Content Type
5784	   provides a "standard mechanism for doing non-standard things". This
5785	   extension support is provided for implementers to "push the envelope"
5786	   on the existing version of the memo. Extension properties are
5787	   specified by property and/or property parameter names that have the
5788	   prefix text of "X-" (the two character sequence: LATIN CAPITAL LETTER
5789	   X character followed by the HYPEN-MINUS character). It is recommended
5790	   that vendors concatenate onto this sentinel another short prefix text
5791	   to identify the vendor. This will facilitate readability of the
5792	   extensions and minimize possible collision of names between different
5793	   vendors. User agents that support this content type are expected to
5794	   be able to parse the extension properties and property parameters but
5795	   can ignore them.

5797	   At present, there is no registration authority for names of extension
5798	   properties and property parameters. The data type for this property
5799	   is TEXT. Optionally, the data type can be any of the other valid data
5800	   types.

5802	   Format Definition: The property is defined by the following notation:

5804	     x-prop     = x-name *(";" xparam) [";" languageparam] ":" text CRLF
5805	        ; Lines longer than 75 octets should be folded
5806	   Example: The following might be the ABC vendor's extension for an
5807	   audio-clip form of subject property:

5809	     X-ABC-MMSUBJ;X-ABC-MMSUBJTYPE=wave:http://load.noise.org/mysubj.wav

5811	4.8.8.2 Request Status

5813	   Property Name: REQUEST-STATUS

5815	   Purpose: This property defines the status code returned for a
5816	   scheduling request.

5818	   Value Type: TEXT

5820	   Property Parameters: Non-standard and language property parameters
5821	   can be specified on this property.

5823	   Conformance: The property can be specified in a "VEVENT", "VTODO",
5824	   "VJOURNAL" and "VFREEBUSY" calendar component.

5826	   Description: This property is used to return status code information
5827	   related to the processing of an associated iCalendar object. The data
5828	   type for this property is TEXT.

5830	   The value consists of a short return status, a longer return status
5831	   description, and optionally the offending data. The components of the
5832	   value are separated by the SEMICOLON character (US-ASCII decimal 59).

5834	   The short return status is a PERIOD character (US-ASCII decimal 46)
5835	   separated 3-tuple of integers. For example, "3.1.1". The successive
5836	   levels of integers provide for a successive level of status code
5837	   granularity.

5839	   The following are initial classes for the return status code.
5840	   Individual iCalendar object methods will define specific return
5841	   status codes for these classes. In addition, other classes for the
5842	   return status code may be defined using the registration process
5843	   defined later in this memo.

5845	     |==============+===============================================|
5846	     | Short Return | Longer Return Status Description              |
5847	     | Status Code  |                                               |
5848	     |==============+===============================================|
5849	     |    1.xx      | Preliminary success. This class of status     |
5850	     |              | of status code indicates that the request has |
5851	     |              | request has been initially processed but that |
5852	     |              | completion is pending.                        |
5853	     |==============+===============================================|
5854	     |    2.xx      | Successful. This class of status code         |
5855	     |              | indicates that the request was completed      |
5856	     |              | successfuly. However, the exact status code   |
5857	     |              | can indicate that a fallback has been taken.  |
5858	     |==============+===============================================|
5859	     |    3.xx      | Client Error. This class of status code       |
5860	     |              | indicates that the request was not successful.|
5861	     |              | The error is the result of either a syntax or |
5862	     |              | a semantic error in the client formatted      |
5863	     |              | request. Request should not be retried until  |
5864	     |              | the condition in the request is corrected.    |
5865	     |==============+===============================================|
5866	     |    4.xx      | Scheduling Error. This class of status code   |
5867	     |              | indicates that the request was not successful.|
5868	     |              | Some sort of error occurred within the        |
5869	     |              | calendaring and scheduling service, not       |
5870	     |              | directly related to the request itself.       |
5871	     |==============+===============================================|

5873	   Format Definition: The property is defined by the following notation:

5875	     rstatus    = "REQUEST-STATUS" rstatparam ":"
5876	                  statcode ";" statdesc [";" extdata]

5878	     rstatparam = [";" languageparm]
5879	                  *(";" xparam)

5881	     statcode   = 1*DIGIT *("." 1*DIGIT)
5882	     ;Hierarchical, numeric return status code

5884	     statdesc   = text
5885	     ;Textual status description

5887	     extdata    = text
5888	     ;Textual exception data. For example, the offending property
5889	     ;name and value or complete property line.

5891	   Example: The following are some possible examples of this property.
5892	   The COMMA and SEMICOLON separator characters in the property value
5893	   are BACKSLASH character escaped because they appear in a  text value.

5895	     REQUEST-STATUS:2.0;Success

5897	     REQUEST-STATUS:3.1;Invalid property value;DTSTART:96-Apr-01

5899	     REQUEST-STATUS:2.8; Success\, repeating event ignored. Scheduled
5900	      as a single event.;RRULE:FREQ=WEEKLY\;INTERVAL=2

5902	     REQUEST-STATUS:4.1;Event conflict. Date/time is busy.

5904	     REQUEST-STATUS:3.7;Invalid calendar user;ATTENDEE:
5905	      MAILTO:jsmith@host.com

5907	5  iCalendar Object Examples

5909	   The following examples are provided as an informational source of
5910	   illustrative iCalendar objects consistent with this content type.

5912	   The following example specifies a three-day conference that begins at
5913	   8:00 AM EDT, September 18, 1996 and end at 6:00 PM EDT, September 20,
5914	   1996.

5916	     BEGIN:VCALENDAR
5917	     PRODID:-//xyz Corp//NONSGML PDA Calendar Verson 1.0//EN
5918	     VERSION:2.0
5919	     BEGIN:VEVENT
5920	     DTSTAMP:19960704T120000Z
5921	     UID:uid1@host.com
5922	     ORGANIZER:MAILTO:jsmith@host.com
5923	     DTSTART:19960918T143000Z
5924	     DTEND:19960920T220000Z
5925	     STATUS:CONFIRMED
5926	     CATEGORIES:CONFERENCE
5927	     SUMMARY:Networld+Interop Conference
5928	     DESCRIPTION:Networld+Interop Conference
5929	       and Exhibit\nAtlanta World Congress Center\n
5930	      Atlanta, Georgia
5931	     END:VEVENT
5932	     END:VCALENDAR

5934	   The following example specifies a group scheduled meeting that begin
5935	   at 8:30 AM EST on March 12, 1998 and end at 9:30 AM EST on March 12,
5936	   1998. The "Organizer" has scheduled the meeting with one or more
5937	   calendar users in a group. A time zone specification for Eastern
5938	   United States has been specified.

5940	     BEGIN:VCALENDAR
5941	     PRODID:-//RDU Software//NONSGML HandCal//EN
5942	     VERSION:2.0
5943	     BEGIN:VTIMEZONE
5944	     TZID:Eastern US
5945	     BEGIN:STANDARD
5946	     DTSTART:19981025T020000
5947	     RDATE:19981025T020000
5948	     TZOFFSETFROM:-0400
5949	     TZOFFSETTO:-0500
5950	     TZNAME:EST
5951	     END:STANDARD
5952	     BEGIN:DAYLIGHT
5953	     DTSTART:19990404T020000
5954	     RDATE:19990404T020000
5955	     TZOFFSETFROM:-0500
5956	     TZOFFSETTO:-0400
5957	     TZNAME:EDT
5958	     END:DAYLIGHT
5959	     END:VTIMEZONE
5960	     BEGIN:VEVENT
5961	     DTSTAMP:19980309T231000Z
5962	     UID:guid-1.host1.com
5963	     ORGANIZER;ROLE=CHAIR:MAILTO:mrbig@host.com
5964	     ATTENDEE;RSVP=TRUE;ROLE=REQ-PARTICIPANT;CUTYPE=GROUP:
5965	      MAILTO:employee-A@host.com
5966	     DESCRIPTION:Project XYZ Review Meeting
5967	     CATEGORIES:MEETING
5968	     CLASS:PUBLIC
5969	     CREATED:19980309T130000Z
5970	     SUMMARY:XYZ Project Review
5971	     DTSTART;TZID=US-Eastern:19980312T083000
5972	     DTEND;TZID=US-Eastern:19980312T093000
5973	     LOCATION:1CP Conference Room 4350
5974	      END:VEVENT
5975	     END:VCALENDAR

5977	   The following is an example of an iCalendar object passed in a MIME
5978	   message with a single body part consisting of a "text/calendar"
5979	   Content Type.

5981	     TO:jsmith@host1.com
5982	     FROM:jdoe@host1.com
5983	     MIME-VERSION:1.0
5984	     MESSAGE-ID:<id3@host1.com>
5985	     CONTENT-TYPE:text/calendar

5987	     BEGIN:VCALENDAR
5988	     METHOD:xyz
5989	     VERSION:2.0
5990	     PRODID:-//ABC Corporation//NONSGML My Product//EN
5991	     BEGIN:VEVENT
5992	     DTSTAMP:19970324T1200Z
5993	     SEQUENCE:0
5994	     UID:uid3@host1.com
5995	     ORGANIZER:MAILTO:jdoe@host1.com
5996	     ATTENDEE;RSVP=TRUE:MAILTO:jsmith@host1.com
5997	     DTSTART:19970324T123000Z
5998	     DTEND:19970324T210000Z
5999	     CATEGORIES:MEETING,PROJECT
6000	     CLASS:PUBLIC
6001	     SUMMARY:Calendaring Interoperability Planning Meeting
6002	     DESCRIPTION:Discuss how we can test c&s interoperability\n
6003	      using iCalendar and other IETF standards.
6004	     LOCATION:LDB Lobby
6005	     ATTACH:file:///xyzCorp.com/conf/bkgrnd.ps
6006	     END:VEVENT
6007	     END:VCALENDAR

6009	   The following is an example of a to-do due on April 15, 1998. An
6010	   audio alarm has been specified to remind the calendar user at noon,
6011	   the day before the to-do is expected to be completed and repeat
6012	   hourly, four additional times. The to-do definition has been modified
6013	   twice since it was initially created.

6015	     BEGIN:VCALENDAR
6016	     VERSION:2.0
6017	     PRODID:-//ABC Corporation//NONSGML My Product//EN
6018	     BEGIN:VTODO
6019	     DTSTAMP:19980130T134500Z
6020	     SEQUENCE:2
6021	     UID:uid4@host1.com
6022	     ORGANIZER:MAILTO:unclesam@us.gov
6023	     ATTENDEE;PARTSTAT=ACCEPTED:MAILTO:jqpublic@host.com
6024	     DUE:19980415T235959
6025	     STATUS:NEEDS-ACTION
6026	     SUMMARY:Submit Income Taxes
6027	     BEGIN:VALARM
6028	     ACTION:AUDIO
6029	     TRIGGER:19980403T120000
6030	     ATTACH:http://host.com/pub/audio-files/ssbanner.wav
6031	     REPEAT:4
6032	     DURATION:PT1H
6033	     END:VALARM
6034	     END:VTODO
6035	     END:VCALENDAR

6037	   The following is an example of a journal entry.

6039	     BEGIN:VCALENDAR
6040	     VERSION:2.0
6041	     PRODID:-//ABC Corporation//NONSGML My Product//EN
6042	     BEGIN:VJOURNAL
6043	     DTSTAMP:19970324T120000Z
6044	     UID:uid5@host1.com
6045	     ORGANIZER:MAILTO:jsmith@host.com
6046	     STATUS:DRAFT
6047	     CLASS:PUBLIC
6048	     CATEGORY:Project Report, XYZ, Weekly Meeting
6049	     DESCRIPTION:Project xyz Review Meeting Minutes\n
6050	      Agenda\n1. Review of project version 1.0 requirements.\n2.
6051	     Definition
6052	      of project processes.\n3. Review of project schedule.\n
6053	      Participants: John Smith, Jane Doe, Jim Dandy\n-It was
6054	       decided that the requirements need to be signed off by
6055	       product marketing.\n-Project processes were accepted.\n
6056	      -Project schedule needs to account for scheduled holidays
6057	       and employee vacation time. Check with HR for specific
6058	       dates.\n-New schedule will be distributed by Friday.\n-
6059	      Next weeks meeting is cancelled. No meeting until 3/23.
6060	     END:VJOURNAL
6061	     END:VCALENDAR

6063	   The following is an example of published busy time information. The
6064	   iCalendar object might be placed in the network resource
6065	   www.host.com/calendar/busytime/jsmith.ifb.

6067	     BEGIN:VCALENDAR
6068	     VERSION:2.0
6069	     PRODID:-//RDU Software//NONSGML HandCal//EN
6070	     BEGIN:VFREEBUSY
6071	     ORGANIZER:MAILTO:jsmith@host.com
6072	     DTSTART:19980313T141711Z
6073	     DTEND:19980410T141711Z
6074	     FREEBUSY:19980314T233000Z/19980315T003000Z
6075	     FREEBUSY:19980316T153000Z/19980316T163000Z
6076	     FREEBUSY:19980318T030000Z/19980318T040000Z
6077	     URL:http://www.host.com/calendar/busytime/jsmith.ifb
6078	     END:VFREEBUSY
6079	     END:VCALENDAR

6081	6  Recommended Practices

6083	   These recommended practices should be followed in order to assure
6084	   consistent handling of the following cases for an iCalendar object.

6086	   1.      Content lines longer than 75 octets SHOULD be folded.

6088	   2.      A calendar entry with a "DTSTART" property but no "DTEND" property
6089	     - The event does not take up any time. It is intended to represent
6090	     an event that is associated with a given calendar date and time of
6091	     day, such as an anniversary. Since the event does not take up any
6092	     time, it MUST NOT be used to record busy time no matter what the
6093	     value for the "TRANSP" property.

6095	   3.      When the "DTSTART" and "DTEND", for "VEVENT", "VJOURNAL" and
6096	     "VFREEBUSY" calendar components, and "DTSTART" and "DUE", for
6097	     "VTODO" calendar components, have the same value data type (e.g.,
6098	     DATE-TIME), they SHOULD specify values in the same time format
6099	     (e.g., UTC time format).

6101	   4.      A combination of "RRULE" and "RDATE" properties that produces more
6102	     than one instance for a given date/time - Only one recurrence can
6103	     occur on a given date/time interval. Just one instance for the
6104	     date/time is recorded.

6106	   5.      A particular iCalendar object method that specifies "ATTENDEE"
6107	     properties with the "MEMBER" property parameter, for which the
6108	     recipient has multiple memberships - Recipient should reply to
6109	     only the first "MEMBER" property parameter value that it can
6110	     match.

6112	   6.      An implementation can truncate a "SUMMARY" property value to 255
6113	     characters.

6115	   7.      If seconds of the minute are not supported by an implementation,
6116	     then a value of "00" should be specified for the seconds component
6117	     in a time value.

6119	   8.      If the value type parameter (VALUE=) contains an unknown value
6120	     type, it should be treated as TEXT.

6122	   9.      TZURL values SHOULD NOT be specified as a FILE URI type. This URI
6123	     form can be useful within an organization, but is problematic in
6124	     the Internet.

6126	   10.       Some possible English values for CATEGORIES property include
6127	     "ANNIVERSARY", "APPOINTMENT", "BUSINESS", "EDUCATION", "HOLIDAY",
6128	     "MEETING", "MISCELLANEOUS", "NON-WORKING HOURS", "NOT IN OFFICE",
6129	     "PERSONAL", "PHONE CALL", "SICK DAY", "SPECIAL OCCASION",
6130	     "TRAVEL", "VACATION". Categories can be specified in any
6131	     registered language.

6133	   11.       Some possible English values for RESOURCES property include
6134	     "CATERING", "CHAIRS", "COMPUTER PROJECTOR", "EASEL", "OVERHEAD
6135	     PROJECTOR", "SPEAKER PHONE", "TABLE", "TV", "VCR", "VIDEO PHONE",
6136	     "VEHICLE". Resources can be specified in any registered language.

6138	7  Registration of Content Type Elements

6140	   This section provide the process for registration of MIME Calendaring
6141	   and Scheduling Content Type iCalendar object methods and new or
6142	   modified properties.

6144	7.1 Registration of New and Modified iCalendar Object Methods

6146	   New MIME Calendaring and Scheduling Content Type iCalendar object
6147	   methods are registered by the publication of an IETF Request for
6148	   Comment (RFC). Changes to an iCalendar object method are registered
6149	   by the publication of a revision of the RFC defining the method.

6151	7.2 Registration of New Properties

6153	   This section defines procedures by which new properties or enumerated
6154	   property values for the MIME Calendaring and Scheduling Content Type
6155	   can be registered with the IANA. Non-IANA properties can be used by
6156	   bilateral agreement, provided the associated properties names follow
6157	   the "X-" convention.

6159	   The procedures defined here are designed to allow public comment and
6160	   review of new properties, while posing only a small impediment to the
6161	   definition of new properties.

6163	   Registration of a new property is accomplished by the following
6164	   steps.

6166	7.2.1   Define the property

6168	   A property is defined by completing the following template.

6170	     To: ietf-calendar@imc.org

6172	     Subject: Registration of text/calendar MIME property XXX

6174	     Property name:

6176	     Property purpose:

6178	     Property value type(s):

6180	     Property parameter (s):

6182	     Conformance:

6184	     Description:

6186	     Format definition:

6188	     Examples:

6190	   The meaning of each field in the template is as follows.

6192	   Property name: The name of the property, as it will appear in the
6193	   body of an text/calendar MIME Content-Type "property: value" line to
6194	   the left of the colon ":".

6196	   Property purpose: The purpose of the property (e.g., to indicate a
6197	   delegate for the event or to-do, etc.). Give a short but clear
6198	   description.

6200	   Property value type (s): Any of the valid value types for the
6201	   property value needs to be specified. The default value type also
6202	   needs to be specified. If a new value type is specified, it needs to
6203	   be declared in this section.

6205	   Property parameter (s): Any of the valid property parameters for the
6206	   property needs to be specified.

6208	   Conformance: The calendar components that the property can appear in
6209	   needs to be specified.

6211	   Description: Any special notes about the property, how it is to be
6212	   used, etc.

6214	   Format definition: The ABNF for the property definition needs to be
6215	   specified.

6217	   Examples: One or more examples of instances of the property needs to
6218	   be specified.

6220	7.2.2   Post the Property definition

6222	   The property description MUST be posted to the new property
6223	   discussion list, ietf-calendar@imc.org.

6225	7.2.3   Allow a comment period

6227	   Discussion on the new property MUST be allowed to take place on the
6228	   list for a minimum of two weeks. Consensus MUST be reached on the
6229	   property before proceeding to the next step.

6231	7.2.4   Submit the property for approval

6233	   Once the two-week comment period has elapsed, and the proposer is
6234	   convinced consensus has been reached on the property, the
6235	   registration application should be submitted to the Method Reviewer
6236	   for approval. The Method Reviewer is appointed to the Application
6237	   Area Directors and can either accept or reject the property
6238	   registration. An accepted registration should be passed on by the
6239	   Method Reviewer to the IANA for inclusion in the official IANA method
6240	   registry. The registration can be rejected for any of the following
6241	   reasons. 1) Insufficient comment period; 2) Consensus not reached; 3)
6242	   Technical deficiencies raised on the list or elsewhere have not been
6243	   addressed. The Method Reviewer's decision to reject a property can be
6244	   appealed by the proposer to the IESG, or the objections raised can be
6245	   addressed by the proposer and the property resubmitted.

6247	7.3 Property Change Control

6249	   Existing properties can be changed using the same process by which
6250	   they were registered.

6252	        1.           Define the change

6254	        2.           Post the change

6256	        3.           Allow a comment period

6258	        4.           Submit the property for approval

6260	   Note that the original author or any other interested party can
6261	   propose a change to an existing property, but that such changes
6262	   should only be proposed when there are serious omissions or errors in
6263	   the published memo. The Method Reviewer can object to a change if it
6264	   is not backward compatible, but is not required to do so.

6266	   Property definitions can never be deleted from the IANA registry, but
6267	   properties which are no longer believed to be useful can be declared
6268	   OBSOLETE by a change to their "intended use" field.

6270	8  References

6272	   The following documents are referred to within this memo.

6274	   [ICMS] "Internet Calendaring Model Specification", Internet-Draft,
6275	   October 1997, ftp://ftp.ietf.org/internet-drafts/draft-ietf-calsch-
6276	   mod-03.txt.

6278	   [IMIP] "iCalendar Message-based Interoperability Protocol (IMIP)",
6279	   Internet Draft, April 1998, http://www.imc.org/draft-ietf-calsch-
6280	   imip-05.txt.

6282	   [ITIP] "iCalendar Transport-Independent Interoperability Protocol
6283	   (iTIP) : Scheduling Events, Busy Time, To-dos and Journal Entries ",
6284	   Internet-Draft, April 1998, http://www.imc.org/draft-ietf-calsch-
6285	   itip-05.txt.

6287	   [ISO 8601] ISO 8601, "Data elements and interchange formats_
6288	   Information interchange--Representation of dates and times",
6289	   International Organization for Standardization, June, 1988. This
6290	   standard is also addressed by the Internet Draft document
6291	   ftp://ds.internic.net/internet-drafts/draft-newman-datetime-00.txt.

6293	   [ISO 9070] ISO/IEC 9070, "Information Technology_SGML Support
6294	   Facilities--Registration Procedures for Public Text Owner
6295	   Identifiers", Second Edition, International Organization for
6296	   Standardization, April 1991.

6298	   [MIME DIR] Howes, T., Smith, M., "A MIME Content-Type for Directory
6299	   Information", Internet-draft-ietf-asid-mime-direct-07.txt, November
6300	   1997.

6302	   [RFC 822] Crocker, D., "Standard for the Format of ARPA Internet Text
6303	   Messages", STD 11, RFC 822, August 1982.

6305	   [RFC 1738] Berners-Lee, T., Masinter, L., McCahill, M., "Uniform
6306	   Resource Locators (URL)", RFC 1738, December 1994.

6308	   [RFC 1766] Alvestrand, H., "Tags for the Identification of
6309	   Languages", March 1995.

6311	   [RFC 2045] Freed, N., Borenstein, N., " Multipurpose Internet Mail
6312	   Extensions (MIME) - Part One: Format of Internet Message Bodies", RFC
6313	   2045, November 1996.

6315	   [RFC 2046] Freed, N., Borenstein, N., " Multipurpose Internet Mail
6316	   Extensions (MIME) - Part Two: Media Types", RFC 2046, November 1996.

6318	   [RFC 2047] Moore, K., "Multipurpose Internet Mail Extensions (MIME) -
6319	   Part Three: Message Header Extensions for Non-ASCII Text", RFC 2047,
6320	   November 1996.

6322	   [RFC 2048] Freed, N., J. Klensin, J. Postel, "Multipurpose Internet
6323	   Mail Extensions (MIME) - Part Four: Registration Procedures", RFC
6324	   2048, January 1997.

6326	   [RFC 2111] "Content-ID and Message-ID Uniform Resource Locators", RFC
6327	   2111, March 1997.

6329	   [RFC 2119] "Key words for use in RFCs to Indicate Requirement
6330	   Levels", RFC 2119, March 1997.

6332	   [RFC 2234] Crocker, D., Overell, P., "Augmented BNF for Syntax
6333	   Specifications: ABNF", RFC 2234, November 1997.

6335	   [RFC 2279] "UTF-8, a transformation format of ISO 10646", RFC 2279,
6336	   January 1998.

6338	   [VCARD] Internet Mail Consortium, "vCard - The Electronic Business
6339	   Card Version 2.1",  http://www.imc.org/pdi/vcard-21.txt, September
6340	   18, 1996.

6342	   [VCAL] Internet Mail Consortium, "vCalendar - The Electronic
6343	   Calendaring and Scheduling Exchange Format",
6344	   http://www.imc.org/pdi/vcal-10.txt, September 18, 1996.

6346	   [XAPIA] "XAPIA CSA, Calendaring and Scheduling Application
6347	   Programming Interface (CSA) Version 1.0", X.400 API Association,
6348	   November 15, 1994.

6350	9  Acknowledgments

6352	   A hearty thanks to the IETF Calendaring and Scheduling Working Group
6353	   and also the following individuals who have participated in the
6354	   drafting, review and discussion of this memo:

6356	   Roland Alden, Harald T. Alvestrand, Eric Berman, Denis Bigorgne, John
6357	   Binici, Bill Bliss, Philippe Boucher, Steve Carter, Andre
6358	   Courtemanche, Dave Crocker, David Curley, Alec Dun, John Evans, Ross
6359	   Finlayson, Randell Flint, Ned Freed, Patrik Falstrom, Chuck
6360	   Grandgent, Mark Handley, Steve Hanna, Paul B. Hill, Paul Hoffman,
6361	   Ross Hopson, Mark Horton, Daryl Huff, Bruce Kahn, C. Harald Koch,
6362	   Ryan Jansen, Don Lavange, Antoine Leca, Theodore Lorek, Steve
6363	   Mansour, Skip Montanaro, Keith Moore, Cecil Murray, Chris Newman,
6364	   John Noerenberg, Ralph Patterson, Pete Resnick, Keith Rhodes, Robert
6365	   Ripberger, John Rose, Doug Royer, Andras Salamar, Ted Schuh, Vinod
6366	   Seraphin, Derrick Shadel, Ken Shan, Andrew Shuman, Steve Silverberg,
6367	   William P. Spencer, John Sun, Mark Towfiq, Yvonne Tso, Robert Visnov,
6368	   James L. Weiner, Mike Weston, William Wyatt.

6370	10 Author's Address

6372	   The following address information is provided in a MIME-VCARD,
6373	   Electronic Business Card, format.

6375	   The authors of this draft are:

6377	     BEGIN:VCARD
6378	     VERSION:2.1
6379	     FN:Frank Dawson
6380	     ORG:Lotus Development Corporation
6381	     ADR;WORK;POSTAL;PARCEL:;6544 Battleford Drive;
6382	      Raleigh;NC;27613-3502;USA
6383	     TEL;WORK;MSG:+1-919-676-9515
6384	     TEL;WORK;FAX:+1-919-676-9564
6385	     EMAIL;INTERNET;PREF:Frank_Dawson@Lotus.com
6386	     EMAIL;INTERNET:fdawson@earthlink.net
6387	     URL:http://home.earthlink.net/~fdawson
6388	     END:VCARD

6390	     BEGIN:VCARD
6391	     VERSION:2.1
6392	     FN:Derik Stenerson
6393	     ORG:Microsoft Corporation
6394	     ADR;WORK;POSTAL;PARCEL:;One Microsoft Way;
6395	      Redmond;WA;98052-6399;USA
6396	     TEL;WORK;MSG:+1-425-936-5522
6397	     TEL;WORK;FAX:+1-425-936-7329
6398	     EMAIL;INTERNET:deriks@Microsoft.com
6399	     END:VCARD

6401	   The iCalendar object is a result of the work of the Internet
6402	   Engineering Task Force Calendaring and Scheduling Working Group. The
6403	   chairman of that working group is:

6405	     BEGIN:VCARD
6406	     VERSION:2.1
6407	     FN:Anik Ganguly
6408	     ORG:OnTime, Inc.
6409	     ADR;WORK;POSTAL;PARCEL:10 Floor;21700 Northwestern Highway;
6410	      Southfield;MI;48075;USA
6411	     TEL;WORK;MSG:+1-248-559-5955
6412	     TEL;WORK;FAX:+1-248-559-5034
6413	     EMAIL;INTERNET:anik@ontime.com
6414	     END:VCARD

6416	11 Full Copyright Statement

6418	   "Copyright (C) The Internet Society (date).  All Rights Reserved.

6420	   This document and translations of it may be copied and furnished to
6421	   others, and derivative works that comment on or otherwise explain it
6422	   or assist in its implmentation may be prepared, copied, published and
6423	   distributed, in whole or in part, without restriction of any kind,
6424	   provided that the above copyright notice and this paragraph are
6425	   included on all such copies and derivative works.  However, this
6426	   document itself may not be modified in any way, such as by removing
6427	   the copyright notice or references to the Internet Society or other
6428	   Internet organizations, except as needed for the purpose of
6429	   developing Internet standards in which case the procedures for
6430	   copyrights defined in the Internet Standards process MUST be
6431	   followed, or as required to translate it into languages other than
6432	   English.

6434	   The limited permissions granted above are perpetual and will not be
6435	   revoked by the Internet Society or its successors or assigns.

6437	   This document and the information contained herein is provided on an
6438	   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
6439	   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
6440	   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
6441	   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
6442	   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.